Dave,
You started this post and in your first sentence you mentioned "last to act with the nuts rule." You will find that wherever that rule can be found, or enforced, it will only pertain to an exclusive nut hand and not your example of the nuts!
Raising in a high low split game, while holding the nut low can prove very expensive when you realise that the other three players have your nut low matched but one player has the high hand all alone! The more you raise, the more you lose.