I'm not sure if his name gets revealed on that particular scene, but later on we see him and Darryl talking, and yeah he's TJ.
Darryl is a guy who is the number 1, the biggest "badass" in the area feeling threatened by the new guy.
New guy that both can challenge him on track and is popular with the ladies.
From his (typical jock) perspective, it's someone new entering his territory and taking what's his.
He didn't know the MC was going to the beach that day when Val joined his group...
But because the MC always hanging out with stunners pisses him off he shoots that snarky look as he walks by, as if to say "i'm gonna get this one before you do".
Obviously not of course, but that's what he's thinking.
There might be a number of things that influence how our relationship with him progresses, maybe it's pushing him off or not, maybe it's winning or losing, maybe it's tipping him
I do think the 2 big ones are:
Valeria route yes or no?
Tori route yes or no?
Those 2 should have the biggest influence on how he behaves with us.