There's no one-size-fits-all explanation for the rationale behind not wanting to people to kneel during the national anthem. If I were to try and give the most basic explanation, it would be that in the US, we are VERY into communal demonstrations of our patriotism (though I like to just call it nationalism). We grow up singing the national anthem in our schools, some of us are taught to never poorly treat a flag, we put the flag on the outside of our homes, our restaurants, our gas stations, we sing the national anthem at any given sporting event even something as small as a YMCA swim meet. So when you get to something as public as a National Football League game, there are bound to be some people shocked that someone would step out of line. People see it as more than just a simple explanation of free speech; it's elevated to the level of a public disturbance.
From there, you can fit people into about 5 groups with varying levels of stupidity and defense:
- There's the people that see the flag as the ultimate symbol of police, military, firefighter service and see disrespect to the flag as the ultimate personal attack against those people. This group loves to ignore the context of the actual message and instead inexplicably sees their misguided world view as universal. Probably the same type of person that would make this argument is the same type of person that would insist that science has answered the question of whether or not the fetus is a human without really thinking critically about why they've come to that conclusion and why others might differ. Their use of people that have given their lives for the country as a shield even though they themselves have probably not done fuck all is really disgusting when you think about it, but the problem is, they don't think about it.
- There's the people that don't want to be reminded when they're enjoying a fun game of CTE-ball about the problems unique to other people. This person is probably most likely to be convinced that there is merit to a person disrespecting the flag, but at the same time, this is the most troubling position for me personally. Nothing is going to get done if this person insists on hiding in their comfortable shell of the US is pretty great.
- There's the people that want minorities to know their place. This is more of a subset of the above, as I have a hard time guessing this group wants understands the plight of the black American, but it also has some additional malice. They know that their comforts are more important than the plight of others and will put a temp. stop to free speech to keep it that way. This group is logically inconsistent, malicious, and the kind of people you definitely don't want to be friends with.
- There's the crazies, who will say that an attack on the flag is an attack on free speech or an incitement of violence, whatever that means. They haven't thought critically about shit.
- And there's the ignorant people, who don't know what the fuck is going on but they default to my original explanation that someone is stepping out of line in a public display of patriotism and that is bad for reasons.
Reasoning with any of these people is really tough. I've tried. People just see the flag as the coolest thing ever and formulate their own narrative on what the person was attacking and how and why. The most success I've had is to convince the person that they're not leaving the "attacker" with very many options, and that in itself is in contrast to the spirit of free speech. If disrespecting the flag gets people talking and no one directly was hurt, how is that a bad thing? You could've chosen to ignore this, but you decided not to and now you know more about their message and you can reasonably go on with your life EVEN if you're military.