That's just the excuse in this particular case.
They don't believe POC deserve a voice or a right to protest in any way, shape or form. It's all wrong to them, because to them POC deserve every injustice and inequity, i.e. Michael Bennett deserving police brutality because the police have a difficult job and Bennett 'looked like the perp'. Then they'll browbeat you with tales of how great the country is and you should be more grateful.
Oh for sure. I mean just based on the people I know that say this, they are lying to themselves. What it really comes down to is seeing a Black man that is successful not being grateful for it. After all, they are White, and yet they aren't rich. No seriously, that's the impression I get.
Nonetheless, the lie they go with, that it's about respecting America and that's the most important thing, is hypocritical when they usually value freedom of speech above all else even with genocide loving Nazis.
Though to also be fair, and I can speak for this, is that some of it comes down to that Americans are taught to never go against America in anyway, to show patriotism at all times, and that the Flag and the anthem are basically to be worshiped. As such, thinking critically about it is hard for a lot of people.