Is this reportable?

[Lithera]

Advertising for your guild in another game IS against the TOS, for the simple reason that S-E can't verify that you aren't, for example, an employee of that other game's company and would be earning a direct financial benefit to getting people to play it. Rule of thumb is, if it's a game that's not by S-E, safer to not publicly mention it at all.

This. That GM handled things exactly as they should have. Had they posted the exact section of the ToS (the one quoted in this thread), the player likely would have just gotten more mouthy. Instead the GM kept it civil, gave out a warning, and sent them on their way despite some of the smartass comments.