It has everything to do with disrespecting your country, flag and those that died for this country. We are still the greatest country in the world, not really even close IMO. Find another way to protest. If I were a coach/administrator they would not play and scholarships would be pulled.
Let me first say that most normal people can agree that there are racist people in this world. You will never be able to legislate this out of society's. Racism and hatred are taught emotions by uneducated closed minded bigoted people. IMO the only way to fix this and it may never be, is by education.
Now lets get into the reason why this originally came to the forefront. It came to be, by a lie that was spread by the left wing political party including our former president about a little incident in Ferguson, MO. The incident was touted that a black man was unjustly shot by a white cop for no reason. The hype was built up to a frenzied level by the left hype machine which caused riots, destruction and helped to further pull sides apart. It turned out and was proven by independent federal investigators that were in part brought on by the Obama administration that this was completely false. It was just another thug and that turned and charged an officer. If he would have taken a knee and obeyed the law, he would be alive today. Yes I know there are bad people in every segment of our country. There are bad officers in the police force. Convict and punish those bad seeds.
The attitude from the left and right are pushing people further and further apart. The bigmouths form both sides are weakening our country, where most of the answers or somewhere in the middle of these two groups not out on the extremes.