After reading this entire thread I think it would be much more efficient to post on wow forums and ask for a blues response on vanilla IS being bannable or not. I'm guessing the answer would be no as long as no addons that violated the TOS was used. Blues may not respond on it, though, due to the author also developing a way to hide from warden.

I just searched wow forums and can't find anyone even asking if vanilla IS is bannable or not.