Anon didn’t make up the rules, and I wouldn’t wager that he was the one who decided to start that game. Everyone chose to play knowing they wouldn’t be comfortable getting anon. It doesn’t seem to me like anon made any advance at all. Rejecting someone’s advances for whatever reason is not morally incorrect, nor is denying them physical displays of affection. But going up to someone unprompted and telling them you find them unattractive and wouldn’t feel comfortable touching them is. This seem like an intermediate situation where they willingly and knowingly created a situation where they would have to do the latter. Refusing to kiss or touch anon wasn’t the fault here, initiating the game was.
It sounds like he joined (sat down into) an existing game, which if this story was true, which it isn’t, because it’s 4chan, would be pretty different?