I have been part of the big flag ceremony on the field before a Broncos' game and take seriously the flag and everything for which it stands. I have worn it on my Army uniform for 8 years. I fly the flag on my home (with lights and a weather proof flag). 

Still, I think it's wrong (even if legal) to force someone to pretend to be patriotic. In my opinion, a player should have the option of staying in the locker room if they so choose. I understand working for an employer and following the rules but in this case, I think the rule is wrong.