I think this is mostly wishful thinking, by people who are too horrified to admit that their tribe can be doing bad and so blame “outsiders”.
That's called projection, on your part.
I don't think anybody supporting the protesters is horrified that some of the "legitimate" protesters are looting. They're more horrified by the systematic abuse and lack of accountability that has sparked these protests.
Your insistence on focusing on the violence is a cheap distraction.