This may have an obvious response, but I can't quite see it: If the worst possible thing is a negligible change, an easily achievable state, shouldn't an AGI want to work to prevent that catastrophic risk? Couldn't this cause terribly conflicting priorities?
If there is a minor thing that the AGI despises above all, surely some joker will make a point of trying to see what happens when they instruct their local copy of Marsupial-51B to perform the random inconsequential action.
It might be tempting to try to compromise on utopia to avoid a strong risk of the literal worst possible thing.
Apologies if there's a reason why this is obviously not a concern :)
Nuclear warnings have been overused a little by some actors in the past, such that there's a credible risk of someone calling the bluff and continuing research in secrecy, knowing that they will certainly get another warning first, and not immediately a nuclear response.
If you have intelligence that indicates secret ASI research but the other party denies, at which point do you fire the nukes?
I expect they would be fired too late, with many months of final warnings before.