IMHO these sorts of issues become clearer if you ask "where is the victim".
Where is the victim?
I have a separate but connected query for you: if there were a vaccine to prevent HPV infection, including the variants associated with most cervical cancers, but only if it is given before infection occurs which has an association with sexual activity: would it be OK to make it compulsory for girls under the age of 12 to help stop the huge increase in aggressive cervical cancer we're seeing in young women? (The vaccine is called Gardasil, fwiw) ... or how about vaccinating boys on the assumption that those dirty dogs are where the girls are getting it from?
"... They ne'er cared for us
yet: suffer us to famish, and their store-houses
crammed with grain; make edicts for usury, to
support usurers; repeal daily any wholesome act
established against the rich, and provide more
piercing statutes daily, to chain up and restrain
the poor. If the wars eat us not up, they will; and
there's all the love they bear us."
-- Shakespeare: Coriolanus, Act 1, scene 1