Jesus. Mapplethorpe didn't do Piss Christ. It was Andres Serrano. It is not a piece I like, but it is certainly art. Charlie Hebdo is a bunch of communists, but I have no problem with their cartoons. I think they consider them satire, not art, so I will go with that.
I think you should be able to burn both flag and banner, as long as it is yours, which was the problem in the BLM case you are talking about. The banner wasn't the property of the burner. I detest BLM, and detest burning the American flag.
Thank you for your support. I will reciprocate in telling you that I support your right to be factually wrong on just about everything, but still to see yourself as enlightened.