Chumley Chumley:
He seemed pretty pissed off about something right from the get go, and toward the end of the interview Jian asked him if he was pissed off because he had said this was a hobby for him or something to that effect. I didn't recall hearing that in the clip, and when I rewound it I couldn't find it, though it looked like there was a segment cut out. If Thorton was always serious about becoming a musician and was sidetracked by his acting , I could see why he was pissed off by a comment like that. Still, he should have dealt with the comment right away instead of sulking about it. His band looked very uncomfortable.
He was pissed off because the journalist wasn't suppose to mention Billy's acting career and he did. He wants recognition for their band because they are "good" musicians that make good music and not because he happens to be an actor who won some oscars and banged Angelina, that now happens to be in a band.
He wants the music to attract attention not the actor in a band.
Unfortunately for him human beings retain information.