Its a good point, LdN. If you legitimately approach a patron and ask for corrective action, what are you supposed to do if they say 'no'? You ask them to leave. If they do not, your only recourse is to call the police. You cannot take matters into your own hands. Reminiscent of the Starbucks issue recently.
Whether right or wrong, it is not a patrons place to open The People's Court in a private location. Or Judge Judy.
Once someone says, if you do not leave this private property I will call the police, you leave.
I don't know the specifics of this particular case, but they can follow-up after the event with whatever attorney ambulance chaser they want.
There seems to be a problem today with patrons not understanding private vs. public property. And, in either case, if the police ask you to leave or face arrest those are your options. Period.
LdN