Please for the love of everything holy do not start denying rides to anyone.
I fly for SWA and anyone not on "the list" is welcome in my JS or any seat on the airplane. I probably average 1-2 United guys a trip due to where I am based. All comers are welcome. Let's educate the offender and move on.
And yeah, solving issues between pilots should start face to face and escalate from there. Going to the cops isn't a good look.