They did reject pedophilia as a legitimate sexual choice—but not, as one might hope, through thoughtful application of moral principles to sexual behavior. Rather, they simply declared that minors are by definition unable to give consent.

I don't see the objection here? What "moral principles of sexual behavior" are we talking about, other than informed consent? The fact that it grosses out or makes uncomfortable someone who is not involved, or arguments from "nature" or "social norms", are not valid objections in my opinion.

The only standard that makes sense is, "Are all participants willing, aware of the risks, and not being coerced nor defrauded." Actually, I'd say that goes for any human interaction, sexual or not.