I agree! It appears he is doing it for the "shock value" which is very disrespectful to you and not a healthy thing. I don''t know that I would even feel comfortable having him in my home at this time. Definitely tell him your feelings on this, and that if he cannot control these urges around you, then he is not welcome until he gets help.
I would tell him in a very straight forward way that it makes you very uncomfortable and that if he is going to stay with you he needs to respect your boundaries. You might also suggest counseling as this does not seem like normal behavior at all. Good luck!