Your opinion on the matter doesn't matter because no matter how you try to explain it, it doesn't matter. No employee in the United States of America has the right to protest at their workplace. And every employer in America has the right to fire any employee that attempts to protest in their workplace.
There's no two sides to this. Not being able to protest at work is a fact that can't be disputed ever.
It’s not as simple as NFL players being at work and protesting, this is more of a gray area due to the fact these are collectively bargained employees.
The CBA is ambiguous at best on anthem protests, leaving the door open for players to protest. The CBA does have a provision stating employees can be fined, suspended, terminated, etc for conduct detrimental to the brand. This could be one approach the NFL could use, but it’s also a gray area. The NFL could point to ratings and sponsorship being down, but the players could point to ratings being down less than other programming and continued increases in revenue, overall team values and salary cap. There are similar provision in the employment contract players must sign with the league, but they would be open to the same scrutiny.
The players manual, which is not collectively bargained, does comment on conduct during the anthem, but unlike the NBA, the NFL fucked up the wording leaving a loophole by suggesting players “should” stand versus “must” stand. The NFL had a chance to shut this down immediately and get in front of it, but has continuously fucked it up every step of the way. The fact the NFL and Goddell basically endorsed this on several occasions gives the Union strong standing moving forward.
The NFL could still have strong grounds to terminate, legally, but they could be stuck paying out contracts, even non-guaranteed monies, and could face significant EEOC litigation if they pick and choose termination, which could be viewed as discriminatory.