*deep breath*
Alright. I'll stop with the raging and stuffposting if everyone else does.
FlatFlyer posts about birds a lot. Ok. Cool. Just because you don't like it or find it annoying doesn't give you any right to tell him he has to stop it. That's oppressive, selfish and unreasonable. The internet is not a dictatorship, it's a free, public ground and this is a (semi) public forum. You can be a birdbrain if you want, there are no rules saying you cannot be yourself.
Just because the internet is open doesn't mean you can frequently shove your love for things down peoples' throats. On this forum and others, that's the purpose of megathread. Bronies and furries keep their content in a megathread and they don't post about it elsewhere. Same thing applies. It's annoying when someone constantly just keeps posting about their passion for birds or other stuff. Yes, it is flaunting it around and of course it is frowned upon.
If flat was actively trying to cause problems by doing this it would be an entirely different story, but he isn't, he's just being himself. If you don't like it, the right thing to do would be to simply ignore him and move on, but you people are instead trying to bully him into changing his ways against his will. And I don't think that's right.
We aren't telling him to not express himself, we are complaining about him posting bird-related posts everywhere. And really, bully him? You're still on this, holy crap, it's a complaint, not an attack. Ignoring the problem is not a solution, he would just keep repeating the problem without someone stepping in and telling him, y'know what, you shouldn't post about birds everywhere. So yes, he is actively causing problems because he didn't stop.