It actually may work. But not because aliens will come to save us - there is no time. But because any signal we send in space will reach any star before intelligence explosion wave, and thus aliens may know potentially hostile nature of our AI.
Our AI will know all this, and if it wants to have better relation with aliens, it may invest some resources in simulating friendliness. Cheap for AI, cheap for us.
So imagine you're living like you are, today, and somehow some message appears from a remote tribe that has never had contact with civilization before. The message reads "help! We've discovered fire and it's going to kill us! Help! Come quick!"
What do you do?
I'm not sure how you envision "sending signals into space" as noticeably different from what we've been doing for the last 100 years or so. Any civilization close enough to hear a more directed plea, and advanced enough to intervene in any way, is already monitoring the Internet and knows whatever some subset of us could say.
Desiderata for an alien civ that saves us:
up to y'all whether the intersection of these criteria sounds likely
Let's assume that Eliezer is right: soon we'll have an AGI that is very likely to kill us all. (personally, I think Eliezer is right).
There are several ways to reduce the risk, in particular: speeding up alignment research and slowing down capabilities research, by various means.
One underexplored way to reduce the risk is active SETI (also known as METI).
The idea is as follows:
The main advantage of the method is that it can be implemented by a small group of people within a few months, without governments and without billions of dollars. Judging by the running costs of the Arecibo Observatory, one theoretically can rent it for a year for only $8 million. Sending only a few hundred space messages could be even cheaper.
Obviously, the method relies on the existence of an advanced alien civilization within a few light years from the Earth. The existence seems to be unlikely, but who knows.
Is it worth trying?