A "binding" treaty where the terms of the treaty are supposedly binding, but, like on the real world stage, the only penalties for breaking them is a lowered trust from all the other countries/players, sounds fine.

A binding treaty where if you break them someone will say "that's against the rules of the game, and the rest of us will stop playing if you don't comply" sounds terrible.

That’s an example of lowered trust, not of the other players leaving the planet (or persuading the US to do so).

Agreeing to a shared ledger system is absolutely a game. See Conway for details.

Fair enough, I was thinking of the game as ‘risk irl’ but if it’s just a game of Shared Ledger then they absolutely can/will leave.