Sure- it's within his rights to not stand during the National Anthem, whatever.
It's also within anyone's rights to walk around calling everyone they see an asshole.
Just because you can do something, doesn't mean it's right and it doesn't mean it's not disrespectful.
I mean, there's civil disobedience, and then there's this attention grabby bullshit.
I too enjoy hearing about oppressed minorities from multi-million dollar contracted sports entertainers.