Taking a knee is not to disrespect the flag but to protest injustice.
I say to both. Find a different way.
Firstly, no connection. But in regard to the cops, au contraire. No one would think the cops in that picture should be ticketed. Everyone appreciates the profound tragedy and loss. Even though they aren't masked, if you have a beating heart you'll put that aside for a few minutes.
Now apply the same humanity to other humans.