My argument has been threefold here:
1. Unlike Saletan, I do agree with current law that the penalties for sex with a young teen should be similar as penalties for sex with a prepubescent child, without regard to the victim's behavior. You can call one of them an act of hebephilia, and the other an act of pedophilia, but both are child abuse and both do measurable harm, no matter what the victim nominally agreed to. I have detailed my arguments elsewhere, but they can be summed up as: a young teen may physically look somewhat like an adult, but by every other measure (social, emotional, intellectual) they are still a child, and their development can be damaged by sexual interactions with adults, whether "consented" to or not. That argument alone is sufficient reason for the similar penalties.
2. Unlike Saletan, I do not agree that a young teen can consent to an adult, primarily because they cannot understand the consequences of what they are consenting to, or worse, have been previously groomed to respond to adults in a sexual manner. Additionally, because of the inherent power differential between any young teen and any adult (multiplied when the adult is powerful or famous or rich), the teen is particularly susceptible to both implicit and explicit coersion, or even out and out bribery (in the Polanski case, an implied movie career in exchange for sexual favors). We do not allow young teens to consent to a legal contract with an adult, so why would be allow them to consent to a sexual contract with one?
3. While it may be argued that a "normal" adult male could find a young developed teen body attractive, he is also extremely likely to recognize that all the other aspects of her are still those of a child (again - social, emotional, intellectual). Thus a "normal" male should recoil at the idea of actually carrying out a sexual act with a young teen, precisely becuase he should be able to see that she is more than just a body. I would then argue that in those cases where sex did occur, you are looking at a hebephile (or perhaps an all purpose sexual exploiter, someone equally repellent in my book).
On a distantly related note, my personal and admittedly non-medical opinion is that Mr. Polanski is a hebephile, given his documented history of attraction to young teens (and his marriages to very young women). But that is neither here nor there. As Mr Saletan said, the Polanski case is not a good one to use for his arguments about consent.