"Democrats will attack and alienate their core constituencies"
Anecdotal evidence of this: I meet with friends once a week at a bar on a neighborhood "strip" beside one of the larger, public universities in NC ... the crowd is exceedingly entertaining for a political junkie such as myself. It's a "belly of the beast" sort of place for a conservative; unreconstructed hippies who have lived there since their heyday, professors, grad students, a few of the "workers" there openly admit communist sympathies, you get the picture. The Foley topic makes them very uncomfortable. When one tries the standard Dim line about sexual predators, you can just see the eyes flying open, and the faces reddening across the bar.
Interesting reaction, but what do you think they really think? Are they to the left of you and reacting to a "provocation" by a known right-winger? ("Provocation" is a favorite old Pravda chestnut.)
Or are they annoyed by Foley and his behavior, or annoyed by what the Dems are doing? These are leftists, as you describe them. Leftists have a very long history of complete toleration of sexual deviancy, going back to the Bolshevik Revolution and the Nazi bigwigs who used to use the Hitler Youth as their boy-toy seraglio. They may be nowhere near as square-rigged as you evidently hope they are.