Im gonna go ahead and guess it was Brett.

Ah, seems strange to lock something without an explanation. His thread didn't do anything wrong other than say the numbers could be incorect. 

I am a moderator in the making, so let me address the things you brought forward.

This is the post that has an actual "moderated" tag: http://gamrconnect.vgchartz.com/post.php?id=6402235

Although the only thing in there that could lead to a moderation is calling another user's statement delusional. However, I am a believer of "If something is truly delusional, then saying so is an observation, not an insult", so it was harmless. The post you linked shows the continuation of the conversation and you clearly got provoked, yet you were still able to remain as calm as could be reasonably expected. So once again, no penalty for you. As for why exactly you did get banned, I can only guess that the ban reason in your mod history has something substantial to say about your moderation.

As for how careful you should be with these things, users with low post counts and no avatar tend to not care one bit about their profile and reputation, plus there's always a chance that you are dealing with an alt account. I advise caution because sometimes you might even be talking to someone for whom it is a game to bait other users into bans; and before you get dragged too far into it, you should consider to report the offender.