I don't think it's Tsundere per se. He is an immigrant, so he's likely heard much worse than just "country bumpkin" from the kids who were jealous of his talents. It's understandable if he hates them.
He thinks Shenshen is his direct competition for the spot of Male Lead so he is not that friendly with him (he feels Lyouin doesn't have to worry since she is the Female Lead, not knowing Shenshen can dance both), but at the same time he acknowledges that Shenshen is much more talented than him so there's respct too.
That is a good way to look at it too. I'm looking forward to see how their relationship progresses.
I'm glad that senior put that irrelevant mf in his place :p . Major tsundere vibes lol