Yup. That's the core issue here. This is non-consensual involvement of you in their kink. Assuming that these people are what they claim, I'd guess that they are mistaking kink and consent to kink for consent to participate in theirs. There might be some hope for them in the long run, but at the moment they look like beginners to me. If you get the urge to reply, tell her she should be punished by having her picture taken wearing nothing but a pair of roller skates with training wheels on them.