The NFL protest is not a First Amendment issue. Yes, the veterans, and I am one of them, have fought to maintain our individual rights including the right of peaceful dissent.
However, employers have the right to direct the appearance and behavior of their employees in the workplace. They can also hold an employee accountable for off the field behavior if it brings discredit to their organization. Public drunkenness and sexual abuse have been very real examples in the recent past.
In the NFL case, the players are representing their team's expectation of performance and behavior as a condition of their employment. Since all the kneeling players are still on the field we must assume they are representing their employer's views and not just their right of dissent. If this were not the case as with recent cases of dress code and sexual abuse, the offending players should be fined or terminated. Individual players or fans may rationalize that taking a knee is socially necessary, however most see it as a sign of disrespect.
We have a great country, can it be better, yes. But, further division is not the solution. The public ire should be directed at the teams and the league for allowing this behavior to continue. As clients of the teams, league and sponsors, we should uphold our values and take our business elsewhere.