It's not about the forum rules, but rather how not trustworthy you're for the forum community. It's a feedback, not a justice decision.

You have to admit someone cheating other forum users is not going to give trust. Whatever you say, crypto enthusiasts working together or not, people can imagine a lot of different stories. If you say you didn't break any forum rule, he hasn't as well.

Yes, it still a democracy, everyone can say his opinion and he did. It can be rude but.. democracy... You would need a stronger argument other than a "friends working together" to convince him probably