The Haka/Ha'a is a taunt, and the NCAA has said that (taunting) can not do that towards any team - period. I have no problem with it, but rules are rules, and you can't whine when you get penalized, knowing that you will be penalized for doing it towards anyone on the team...
And I understand the "customizing" of it, but really, throat slashing is not symbolic of anything but death, and also another thing the NCAA has said can not be done.
There are ways to do it where it is still meaningful to the team and fans, but still within rules of the NCAA and "acceptable" by other teams fans.