Is impersonating another person against the Terms of Service?

Just got out of a game with two players pretending they were pro players and both of them naturally were pretty huge assholes. They kept posting stream links which clearly was troll because neither were streaming. I find this very offensive because one of the players, who kept claiming he was C9 Sneaky, was basically raging the entire time. I watch C9 Sneaky occasionally and have never seen him rage in this manner and in my opinion this is extremely defaming towards him.

The other guy, who also kept spamming some stream link, I was auto filled into Supporting for. I didn't pick the most conventional Support (however picked a champion I hadn't lost once with yet, mind you) and played like I would any other game. His play style was very non reactive (he would farm while I was trying to engage and ignore me completely). Eventually I ended up dying which put him on tilt. From there the entire game was a nightmare of a raging shit hole as I tried to find farm so I could stay relevant in the game (which made them rage even more, mind you).

Not going to post names or anything, but I'd really love to know.. Is impersonating a "famous" person or player a punishable offense? I really feel like it should be as examples like this are very defaming on another individual.