You should definitely have the same 'cop talk' with them that a black parent has with their kid and for the very same reason. That's what we did. BLM has it's place in the scheme of things but it would be better if their focus could expand to include everyone. I think what's most systemic these days is reactionary authoritarianism. Everywhere you look in the world these days governments seem to be squaring off against their people with most cops dressed up like the Empire's Storm Troopers.
I get no sense of that here. More often than not, demonstrators get away with more than they should.
BLM is about some lives mattering more than others and that is a fact.