I agree and disagree with this. It's all about perspective.
I think the biggest issue here is "Intent vs Opinion". Some (not all I'm sure) are doing this to protest a specific injustice. Their "Intent" is to protest the injustice, not disrespect the flag/country/military.
On the flip side, you have other people's "opinion" that these people are disrespecting the flag/country/military. Now, see there is a huge difference here.
An "Opinion" is inherently not FACT. True "Intent" is FACT. Therefore, everyone getting pissed at people for disrespecting the flag are making up their own rules and trying to enforce their "Opinions" on others rather that paying attention to what is actually happening. (The true FACT of the situation)
See America is about freedom and those wanting to force players to do what in their "Opinion" is correct, are trying to take that freedom away from the players.
If that is the case, then maybe the freedom to be able drive should be removed from those with "Opinions"? Where is the line of fairness if you believe you have the right to take other people's freedom away, but not lose any of your freedoms? It's not and you don't, because that is selfish as hell and not what America is supposed to be all about.