That's what's quite perverse in this case: there are two potential layers of censorship. I don't think the forum management or the forum guidelines are against freedom of speech. It's some users that makes it that way. It's user-based censorship, but made possible by a too sensitive flagging system (and I remember a staff member saying they are aware of that too great sensitivity of the flagging system, but it was for bot/troll control). So it's the users misusing the system, not a voluntary censorship by the site.
Also, there is a the too great acceptance of bullying from a few, by the rest of the forum. I'm surprised how many people deny that it's going on. There can, however, be discussion on how big the problem is, or how organized the bullying is.
So, you can start as many controversial topics you want, as long as it's not clearly with bad intentions, the subjects are not closed by mods/staff. But they get closed by users further down. Not because you created them (in the case of yours), but because someone dared giving their opinion. No reason for you to get into trouble, then. You see what I mean? The fact that the censorship does not really come from the forum rules or guidelines explains why you are not the most targeted even if you are a prolific creator of soon-to-be-closed threads 
Now I do think the forum staff is wrong for closing many of the topics with flagged messages. But as a person who did moderation on many forums, I understand the trade-off. I simply think at this point they are not at the right balance. But it's difficult and time-consuming to improve. The problem may be that the forum is too small to consider paid full-time moderators, and that's almost the only solution. On the most balanced and best forum I've ever moderated, I remember spending hours a days moderating, we were 3 to 5 and all important decisions were taken at least by 2 people and were re-debatable at later stages when other moderators showed up. Ideal, but impossible unless you find several moderators with no life haha. I stopped when I started working, that was only possible when I was a student.
That really depend on personal experiences with forums I suppose. I find this one have relatively low tolerance and diversity, BUT I admit that I'm often on particularly good forums on that aspect, because a lot of my interests bring me to multicultural forums. I totally can imagine that if we take Internet whole, most forums are worse that this one on that point, yes.
