I have noticed lately that xenForo staff can be influenced by some users on their forum to edit and moderate posts that don't agree with what the thread op has posted.
There was a review posted about a forum in the same niche as Forum² that pointed out some of the shortcomings of the site. A few people that were long time members of this site pointed out some of the shortcomings. Staff at xenforo jumped in right away to remove the comments. It seems it's perfectly fine to point out shortcomings of some sites. Just don't do it to any site that is owned by one of the favorites.
You see some of the comments pointed out how the site owner will ban members, some of them long standing members who contributed a good amount to the site, if they post on sites that the owner doesn't approve of. The owner regularly visits sites that he deems bad and if he notices one of his members posting on them he will ban them.
He will also ban you if he doesn't like what you posted on other sites. It seems this guy has nothing better to do then stalk his users and watch everything they do or say.
In any case if you post on the official xenforo forum step lightly if you decide to post an opinion that isn't inline with the way staff thinks.