It is reportable but you have to take into account a couple of things.
- Did he Just say "ggez" without anything uttered before that?
Well in that case I wouldn't really report it.
Reporting for the sake of getting someone punished is not my thing.
It doesn't change the outcome of the game and it really doesn't bother me much.
People like to boast.
- Did he spam emotes, bm and had some toxic remarks before "ggez"?
In that case i would report it. Behaviour like that is sure to tilt anyone.
It probably contributed to your tilt and the reason why you want to report them.
It goes beyond boasting at that point and just serves to insult.
Basically report it if it impacts you.
If it doesn't, just leave it be.
Some people just like to boast and pump their ego.