OzExorcist
Broomcorn's uncle
Bronze Level
It's a lame rule, but from what I can see it can only apply when you have the absolute nuts, with no other possible hands that can beat you, no matter what, AND you are the last player to act.
This is exactly right - it only applies when you've got the nuts and you're last to act.
"Nuts" and "last to act" are very clearly defined terms in poker though. You either have the nuts or you don't. You were either last to act, or you weren't.
As a result the rule is incredibly easy to enforce. If you have an unbeatable hand, you're last to act and you don't bet or raise, you get penalised. Simple as that.