How exactly is a person going to injure themselves by getting naked on camera? Oh, maybe they'll get hypothermia from the chilly air in their bedroom! I genuinely have no idea what you're talking about.
Wouldn't be especially dirty either — nothing a few tissues couldn't wipe away, frankly, not as a solo performer. You get dirtier than that just by using the bathroom.
Plus, sex is just a dirty thing. You have to keep clean and shower a lot. Monitor your health more.
That kind of stuff.