But LEO's just enforce the existing laws, correct? So are you really saying there should be legislation, either at the state or federal level, that describes what is "respectful" and what is not? I believe that has been tried before, it's what Texas vs. Johnson was primarily about: https://en.wikipedia.org/wiki/Texas_v._Johnson#
And I never said burning the American flag as a form of protest was OK. I personally find the act alarming and distasteful. There are types of free speech/expression that I find alarming, but I'm adult enough to know why the 1st Amendment exists, and what would be the repercussions for all Americans if it did not.
In fact I believe that an American who doesn't fully support the 1st Amendment probably shouldn't be living in America.