Wil: "where is the exception that makes the other legal when it breaks one essential rule of the game?"

That's why I want to see the official rules. ;-) I want to see how they define the end of the game and whether that takes precedence over the MDU rule. It's legal to take a man off with a single dice value. If that causes the end of the game and that's that, then the other dice value doesn't matter. The end is the end.

But if not, and the MDU rule is still a requirement, then would indeed be illegal to move directly off with the one dice.

Commonsense gives us the obvious answer. I'd like to see whether the official rules also see it that way.