> if a particularity defined demographic group engages in disproportionate amount of criminal activity (less or more), then wouldn't you expect that that would filter down to the individual interactions?

What you're asking is "is it legitimate to discriminate against individuals because of the demographic group to which they belong".

I realize that it's not obvious that that's the question you're asking. But when reframed in that way, my answer is obviously no. You should engage with an individual if you have evidence of a crime or suspicious activity. Existing while black is neither.