This sentence has structurally the same form. If you think it's ridiculous, it can only be because you think there is something special about sex - i.e. it is sacred in some way. And thus your position actually doesn't relate to free will.
I think you're very confused. Your statements aren't logically consistent and I have to make guesses and leaps of dodgy inference to make any sense of them at all.
I believe you have a prior position on the morality of prostitution and are using arguments you don't understand to defend the position. I think a different tack would be wiser.