Rule 40 is ROMNEY written rules and the RNC can change them anytime they want to.
Rule 40 was written to prevent Ron Paul from being entered into nomination at the convention. The RNC was afraid of some Paulista going off on a conspiracy rant on prime time TV and leaving the impression that we were a little wacky to the watching public. The rule itself only existed in 2012, not anytime before, right back to 1856.