1. I get irritated when presidents get themselves involved in things that are none of their business. I didn't like it when Obama kept involving himself in local and criminal matters because of the race issue - a Beer Summit? Really? - and I don't like it when Trump tells football owners what to do. I don't mind them occasionally getting involved in trivial events - it's a hard calling to have to be presidential 24-7 (though some have managed it). But involving yourself in the argument is unnecessary and should be avoided.
2. People have a right to protest at public events, but when they are at work, not so much. Fans can take a knee at NFL games and no one can say them nay. The referees, vendors, and players are in a different position. We forget this distinction because the work of an entertainer is public, so we slide over into thinking that they have the same rights as a person on their own time. They don't. Their employer owns that time. If you are a comedian or a writer or a musician working your own gig, you can do what you want. But when you are in a stage comedy or playing bassoon for the Boston Pops, you don't automatically get to put up a banner for your own cause. If your employer is okay with that, fine, but you have no free speech right to it.
3. I admit that I very likely carry some extra irritation because the protestors are not fully correct in their complaint, and perhaps less than half-right. That shouldn't matter, but I want to raise my hand here because people want to talk about what I consider to be derivative issues, such as whether this is the best way of achieving your goals.They are complaining about the police, who are not the main culprits in whatever injustice African-Americans experience in the justice system. The Stanford study of Oakland PD that claimed to show that the police are twice as likely to be disrespectful to blacks actually shows they aren't that disrespectful to anyone at all. The injustice is more on the side of being given worse attorneys, harsher sentences, and less-generous parole. Plus, crime against blacks, especially murder, is not solved and consequated as well as crimes against other races. The lower arrest rates compared to the committing of crime means more black families get no answer and no justice. The focus on the police suggests something else is in play, something more personal.