KMG, speaking as a non-officer, I'd be all kinds of relieved if an off-duty officer intervened on my behalf in that sort of scenario, as would most non-criminals, I imagine. Same goes for a carry permit holder, though that has somewhat more potential for things to go legally sideways, simply due to the fact that they don't have arrest powers and that the police would likely then have to investigate instead of simply knowing the facts via being there. As much as I respect and have never personally had a bad interaction with the police, I don't want to be the subject of an investigation if I can avoid it.