Allow me to explain this a bit:

The fact is that it is NOT a violation of the forum rules to have a controversial opinion and post about it.  The problem often comes in when people feel the need to interject that controversial opinion into a discussion of a different topic (even if the topic is related).  Controversial opinions will, by their very nature,  quickly become the focus of a discussion and it doesn't take much to derail a thread with an argument.

Typically when someone gets a warning or a ban of this sort they, for whatever reason, decide that their right to an opinion is being stepped on because they were told their comment was off-topic or trolling in a specific thread.  They base their view of what happened entirely upon their experience of the website and fail to consider that the job of the mods is not to allow every member to speak whatever comes to their mind on each and every topic.  Our goal is to make sure that topics remain relatively on point and that members treat each other with respect.  So what is in reality a forum violation for being posted in the wrong place, is interpreted as an opinion being suppressed.  It's not, it's an opinion being asked to find it's own thread, it's an opinion being asked not to interrupt a discussion that is already taking place so that the on-topic opinions of others can be heard.

Now quickly I want to point out that there is a bit of a fine line between simply having an off-topic comment and trolling.  Generally speaking the troll comments are the ones that include phrasing and wording intended to be abrasive and confrontational, while mundane off-topic comments are typically people just making a comment on a tangent point (which we usually let slide unless the discussion gets derailed as a result). Hallmark differences between a simply off-topic post and a troll post include:  simply off-topic posts give justifications, spell out reasoning, and are making a constructive point..albeit on the wrong topic.  Meanwhile, troll posts are often accusatory, inflammatory, insulting, and/or controversial.

Now having said that, I'm not a head moderator.  I don't oversee the other mods, and I can't affirm the impartiality of every decision they make. But I can tell you that the cases where there is a legitimate question about a moderator's actions should be brought to the attention of a head moderator and, provided you approach it reasonably, you will get a fair hearing.  Simply getting annoyed or upset about what happened but not actually doing anything is actually reinforcing the problem. If there really is a moderator acting inappropriately or enforcing a rule inappropriately then it needs to be corrected.  At the very least you can get a better explanation of how it was handled and hopefully the rule and it's application will then make a bit more sense to you.  Having said that you should always try to pursue the issue with the moderator who issued the warning/ban first and if you feel they're not being helpful or you've reached the limit of what they're willing/able to do then you take it to the head mod.

The bottom line is that everyone is entitled to their opinions here, but you're not entitled to express them in insulting and inflammatory ways and you're not entitled to post them on whichever thread suits your mood.  Hell, if you express your opinions (even the controversial ones) in substantive and constructive forms in the appropriate threads you not only won't be warned or banned but you may very well be on the way to becoming a moderator yourself.

PS - Advice to those who find themselves being warned/banned and have a problem with a moderator, examine your own actions carefully and ask yourself if you could have handled it better.  Then when you have an issue with a moderator you start by acknowledging what you did wrong and how you could have done it better.  This shows you're not just being argumentative but are taking responsibility for your part in the problem even though you may still take issue with something the moderator has done.  I've seen some instances where moderators have gone a bit to far in an issue but I have yet to see the instance where a member was good and truly without fault (though I constantly see cases where they believe that to be the case).

(edit: grammar/spelling issues)

so that's where I left you...