If not following the meta is banable...

It isn't bannable. If your following the hype train of singed. It's not because he played singed support. It's because he went support but did not "support." Picture it this way, imagine if you're in top lane and JG decided he was going to duo with you just because. His role was JG, he ought to live up to those expectations.

He was banned because he got support and decided to jungle. He could have pick Braum or Karma over singed and he still would have got banned

You're literally blowing the case out of hand. And you probably don't know the what happened with that Singed...