"A Manhattan project on AI Alignment, if started now, might still succeed in time. Therefore, the compliance between parties needs not be long-term, which is indeed unlikely to happen."
On what grounds do you base this? You have 3 hypotheticals stacked one on top of the other:
1) AI Alignment is possible
2) AI Alignment is a specific project that may be accomplished before [bad thing happens] if we start now
3) Solving AI Alignment is an actual problem and not just dumb extrapolation from science fiction
Each of these things is totally improbable and the joint probability of them is so astronomically low that you should reconsider your position.