Yes, exactly, you are right.

Obviously "checkpoints" are the solution.
All you have to do is get the network to agree that this "save state" at at this point in time is valid... and then the network remains in consensus.

The thing about @dan is that he's an idealist so it makes sense that he would veto the idea.
Idealism and Reality need to link up somewhere.
Even if one of these checkpoints was corrupt anyone could do a full replay to prove it.
Doesn't seem like a big deal.