I can relate to the OP to some extent. My Former Horrible Boss (FHB) at one point denied a raise to an entire class of people because she overheard one member of said class discussing a purchase in the breakroom (which was next-door to her office) which she disapproved of. In this case, it wasn't morality per se, but rather that she considered this person extravagant, and thus obviously, "[said class of person] don't need a raise, as they have all the money they need, since they can buy [extravagant object]."
In FHB's case, it came from a complete lack of understanding of or respect for any form of boundaries. I spoke to her, and others did as well, about how inappropriate the above decision was, but she never understood what the issue might be. FHB had no issues making the kind of decrees described. Yes, she would declare what was appropriate outside of work hours, and feel free to denigrate someone professionally if they didn't meet her expectations of how to behave outside of work. She did this to me routinely. I wasn't as fit as she thought appropriate, so obviously, I am a lazy, useless person.
If FHB is any guide, the supervisor in this case won't ever "get it." You will have to talk to the supervisor's superiors to get boundaries enforced from above, as they won't ever come from the superior him/herself.