Not sure. This is not to justify rudeness but in the scheme of things that is actually mild compared to some of the stuff others have done or said.
If it were me, I'd say just ignore it and let it pass.
You can always disable chat for a given game.
Most people on this site are generally well behaved and polite imo so good luck with your next opponent.
Cheers.
NEW GAME (152906472) - DelCairos vs. jonjoe (10 0 rated) (win: 11, draw: 3, loss: -5)
jonjoe has joined the chat.
jonjoe: lets go!!!! the computer is giving you break and messing up my moves! AND its still taking you this long
jonjoe: u suck! you wasted the whole game, wasting time
jonjoe: time is part of the game
GAME OVER - DelCairos vs. jonjoe - jonjoe won on time (-5). Your new blitz rating is 1076.
GAME ANALYSIS - Analyze this game - with your opponent | alone
whats up with this fellow ....