For what it's worth, here's an excerpt from my book on historical tax resistance campaigns that makes a similar point:

Radical honesty means abjuring subterfuge—conducting your campaign in the open, in plain sight, without trying to take your opponent by surprise through trickery, and without trying to influence people by “spin” and lopsided propaganda. It also means studiously refusing to participate in the dishonesty by which your opponent holds on to power and deceives those who submit to it. Radical honesty has several potential advantages:

1. Honesty provides a stark moral contrast between your campaign and whatever institution you are opposing.

In The Story of Bardoli, Mahadev Desai described how this played out in the Bardoli tax strike:

…a regular propaganda of mendacity was resorted to [by the Government]. The Government’s way and the people’s way presented a striking study in contrasts. On one side there were secrecy, underhand dealings, falsehood, even sharp practice; on the other there were straight and manly speech, and straight action in broad daylight.

This contrast can make your campaign more appealing to potential resisters and to bystanders, and can increase the morale of the resisters in your campaign.

2. Honesty itself is a threat to tyranny.

The way people signal their loyalty to tyranny is to participate in the lies that bolster its power. When everyone around you goes along with the lies, it feels like everyone is loyal to the tyrant. Czech dissident Václav Havel wrote of how this worked under communist tyranny:

Individuals need not believe all these mystifications, but they must behave as though they did, or they must at least tolerate them in silence, or get along well with those who work with them. For this reason, however, they must live within a lie. They need not accept the lie. It is enough for them to have accepted their life with it and in it. For by this very fact, individuals confirm the system, fulfill the system, make the system, are the system.

But, he said, people may start to refuse:

Living within the lie can constitute the system only if it is universal. The principle must embrace and permeate everything. There are no terms whatsoever on which it can coexist with living within the truth, and therefore everyone who steps out of line denies it in principle and threatens it in its entirety.

Tolstoy went further, and claimed that radical honesty not only threatens tyrants but constitutes a revolution:

No feats of heroism are needed to achieve the greatest and most important changes in the existence of humanity; neither the armament of millions of soldiers, nor the construction of new roads and machines, nor the arrangement of exhibitions, nor the organization of workmen’s unions, nor revolutions, nor barricades, nor explosions, nor the perfection of aërial navigation; but a change in public opinion.

And to accomplish this change no exertions of the mind are needed, nor the refutation of anything in existence, nor the invention of any extraordinary novelty; it is only needful that we should not succumb to the erroneous, already defunct, public opinion of the past, which governments have induced artificially; it is only needful that each individual should say what he really feels or thinks, or at least that he should not say what he does not think.

And if only a small body of the people were to do so at once, of their own accord, outworn public opinion would fall off us of itself, and a new, living, real opinion would assert itself. And when public opinion should thus have changed without the slightest effort, the internal condition of men’s lives which so torments them would change likewise of its own accord.

One is ashamed to say how little is needed for all men to be delivered from those calamities which now oppress them; it is only needful not to lie.

3. Honesty keeps your campaign from deluding itself.

In a tax resistance campaign, as in any activist campaign, there are frequently temptations to take short-cuts. Rather than winning a victory after a tough and uncertain struggle, you can declare victory early and hope to capitalize on the resulting morale boost. Or, rather than doing something practical that takes a lot of thankless hours, you can do something quick and symbolic that “makes a powerful statement.” Or, rather than fighting for goals that are worth achieving, you can pick goals that are easily achievable but that aren’t really worth fighting for.

Radical honesty gets you in the habit of avoiding temptations like these. By facing your situation forthrightly, and by evaluating your tactics unflinchingly and without self-flattery, you become more apt to make effective decisions.

4. Honesty is itself a good thing worth contributing to.

If you conduct your campaign in a radically honest way, you contribute to a cultural atmosphere of trust and straightforward communication. In this way, even if you do not succeed in the other goals of your tax resistance campaign, you still may have some residual positive effect on the world around you.

5. Honesty means there’s a lot you no longer have to worry about.

When you practice radical honesty, you don’t have to worry about keeping your stories straight, you don’t have to worry about leaks of information that might cast doubt on your credibility, you don’t have to be as concerned about information security, and you don’t have to worry about spies and informers in your midst who might blab your secrets to the authorities. This leaves you free to spend your energy and attention playing offense instead of defense.

When Gandhi heard concerns that government agents had infiltrated the Indian independence movement, he wrote:

This desire for secrecy has bred cowardice amongst us and has made us dissemble our speech. The best and the quickest way of getting rid of this corroding and degrading Secret Service is for us to make a final effort to think everything aloud, have no privileged conversation with any soul on earth and to cease to fear the spy. We must ignore his presence and treat everyone as a friend entitled to know all our thoughts and plans. I know that I have achieved most satisfactory results from evolving the boldest of my plans in broad daylight. I have never lost a minute’s peace for having detectives by my side. The public may not know that I have been shadowed throughout my stay in India. That has not only not worried me but I have even taken friendly services from these gentlemen: many have apologized for having to shadow me. As a rule, what I have spoken in their presence has already been published to the world. The result is that now I do not even notice the presence of these men and I do not know that the Government is much the wiser for having watched my movements through its secret agency.

What’s the catch? For one thing, for a campaign to be radically honest it needs to have fairly tight control over its message. Not just anyone can be a spokesperson, but only those with the talent to speak precisely and to cut through the sorts of baloney that characterize political debate in this era of spin doctors and pundits and talking points.

Another difficulty is that if your campaign already has a credibility problem, it’s going to take a lot of radical honesty to dig you out of that hole.

Also, it seems that at least some of the benefits of radical honesty only emerge when it has become really radical and pervasive. Half-hearted gestures of radical honesty are just another form of machiavellian communication. If you’re not prepared to go all the way, it may not be to your advantage to put in the extra effort.