I don't really see why people have a problem with this. Like, I get that the objection is that this reduces her to "sex object" and reducing women to sex objects is something Jezebels usually frown upon...but, then again, isn't that what anyone does to *anyone* when they masturbate to thoughts of them?
Masturbation is a thought exercise, where you're not really concerned about someone's humanity, just their sex appeal. Do I think of Brad Pitt as more than a sex object when I think about him ravishing me late at night? No. Masturbation says little about how you'd treat your actual sex partners, as a whole.
And I don't actually expect that anyone will masturbate to thoughts of her - who isn't doing so already - just because Dan Savage said so.
This "Masturbate to Christine O'Donnell Day" thing isn't really an earnest suggestion at all. It's an attempt to point out the absurdity of her trying to control people's (lustful) thoughts... it's more like satire. And I find that funny.