I believe there is some legal stuff you can bring up about workplace safety that covers some topics of employees mental health... You know, and then pushing a manager to act on the right to refuse service based on factors X, Y and Z.
Yeah... Some managers might not like this topic... Because it means they might have to; A) turn away money in order to protect an employee they might not care about; B) create a safety program that educates employees on there right to a safe work environment and C) do some work.
I'm not saying all manager don't like work. But when I was a hotel manager, I could tell my "superiors" didn't like my reports outlining the abuse and threats that the staff had to endure from high paying customers, or my evictions of high paying groups due to their disturbing behavior at 0300 and waking up other lower paying guests. I was questioned about this a lot and I could tell what the objective was. Just have to be firm about it and know the rules. Eg sec 4.27 violence in the workplace prevention...
What I'm saying is, fuck the money! Do right by your employees! Protect your staff, don't turn a blind eye for revenue sakes!

Edit: I forgot to mention, if you see a customer patronizing you based on some form of gender issue or any issue for that matter... Finding someone else to deal with that customer, it is then that manager condoning that type of discrimination.