I comprehend the context of it very well. As a matter of fact, having studied American Government & History, I understand the fundamentals of Democracy and the foundation that the US was built on, and when I see that people are being suppressed to protest, I see that as a threat to Democracy and the US itself.
Peaceful protest means protesting without the use of violence. It is not limited to marching on the street. There are many forms of peaceful protests. An economic boycott is one example of a peaceful protest in a Democratic society that does not involve marching the streets.
If peaceful protest is restricted to just "marching the street," then this is not a Democracy. It's a form of authoritarian government - the kind of government that the original founders of the US wanted to get away from.
The NFL is publicly traded while the teams are privately owned.
If the team owner decides to penalize his/her own players for exercising Democracy, that is his/her personal choice. That does not mean the action of the team owner is in-line with the values of Democracy.
It's a form of protest - without using any violence. I think most people know that.
One of the best things about a Democratic society (as opposed to an authoritarian society) is that citizens can love the country and still see its flaws, protest, speak out without being retaliated and suppressed (in theory, at least).
When citizens are suppressed and labelled as being "disrespectful" or "unpatriotic" towards the country by disagreeing, then we are moving away from Democracy All that and towards a form of authoritarian government.