There's one critical thing that an accidental domination victory has in common with a "finger flub":
It's known to be against the player's intention in advance.
It is NOT the sort of "strategic error" or "bad roll of the dice" that one must not reload to preserve the integrity of competition.
Now, it's great to get into the habit of not making finger slips, just like it's great to get in the habit of being aware of the threshold for domination victory (2/3 of landmass, right? And initial map settings let you compute how many squares that is within one, in principle?). But what's your reasoning in allowing finger flubs to be reloaded?
Well, I really fail to see how it doesn't apply to reloading accidental domination.
What exactly does banning that accomplish? Let's say 10 people try to milk their game at the threshold of domination victory, but two of them screw up and accidentally trigger domination. Well, with a ban, life for those two people sucks, but otherwise there's no substantial change in the environment, everyone else's scores still have to compete with the other 8 near-dominators.
Seems like nobody actually benefits, instead it just forces more anal play.