Nor have I made a legal threat.  First, I am not among those three people who participated in that visit to the BLM protest.  I have never known any of these people.  I would not be the offended party, in any case.  I've never even lived in Minnesota, or been there in over 30 years or so.  (I made an airplane connection through Minneapolis in about 1985, as I vaguely recall.)  I am not saying there WILL be any sort of legal proceeding; I am merely saying that to cite this claim ("heard the N-word") risks running afoul of being libel.  I think WP rules allow us to express concern that the cite of a vague assertion that somebody "heard the N-word" is problematic from a WP:BLP standpoint.  If multiple BLM protestors claim that they heard one of the (white) visitors say the N-word, and it was cited from some reliable source, that would probably change my opinion.  Can you see why this would be a different situation?