Well I guess I needed to grow up back when too. Back in HS senior year playing b-ball against our biggest rival we were away & a bunch of fans were heckling me, after I got going & dropped 29 points on them, every time down the court playing I'd play with my middle finger up at them. Six years later I'd do the same thing. If you can't take it, don't give it.
The only way I see it as wrong is if it's caught on TV since there's kids watching, then he needs to do one of those "I'm sorry, but don't mean it" press conferences.