This mayhem mechanic is going to have to avoid breaking the golden rule of game design: Don't punish the player for no reason. Otherwise, I can see it being a major issue upon the game's release.
Interesting that you assume that things happening = punishment. I don't see it like that, what I do see and have experiences is the game isn't to go along with turtle mechanics and players ignoring the world while they build up.
In a 4X game, you need stuff happening all the time. If the player turtles and hopes to run down the clock, then things ought to still happen.
Like you know, how countries with perfectly good deals choose for exit in hopes of renegotiating the same deal outside of said union with no guarantee the same deal is even on offer.
That's real life mayhem.