Unless you advertise porn star experience full hour marathon face fucking, he has no business expecting this. So it’s perfectly acceptable to just stand up, kill the vibe and say ‘wow, this is way out of my expertise he he, now let’s move onto what is within my advertised service’.
Clients like him will try to break your boundaries and humiliate you, they don’t care about your comfort and enjoyment, so why should you accommodate their unreasonable demands.