I'm sorry you had that experience. It is your right to deny a service, especially if you're not comfortable with performing it or it just isn't on the menu. Maybe establishing in some manner could help? And have established a rep with regs I'd think in that case (YMMV) would come into play. Regardless the individual is a dbag to not respect that. I wouldn't think that would give you a bad rep at all. If anything that individual could get a bad rep, which would limiting their hobbying. In my opinion at least. I hope you have better luck and have fun
Cheers