People are totally overthinking this. It's a collective noun that was cool 10ish years ago, nothing more, nothing less. (I have white and Asian friends that self-identified their friend groups as their "posses," so I won't let anyone convince me otherwise.) Had Phil said "thugs" or even "gang" there might be an argument as to whether or not he was being intentionally ambiguous, but the word posse does not suggest to me any premeditated jab at LeBron.
This is all pending the interview. If PJ said "LeBron was with his...(dramatic pause)... POSSE," maybe there's something there. If not (which I think the case is), then I chalk it up to: 1) the wonderful, open-to-interpretation-without-context-and-vocal-tonality, full-of-synonyms English language 2) LeBron being easily-offended and trying to make the criticism about race rather than his character