Unless his opponent is a legitimate boxing challenger, I would guess. Rude behavior in any venue is damnable.
OTB, rude people do it verbally and through gestures; on-line, they do it in written form, including the way it is written, etc. 
re: rude behavior
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it's online chess how rude can you be?
i understand, riddick bowe, the world heavyweight boxing champion, is an avid chess player. i would guess he doesn't get too much rude smack talk. at least not otb.