Whenever the Left feels itself in power, it has a natural and inevitable impulse to purge all dissidents. For the Left, Kagan represents the Clinton period, with its welfare reform and Defense of Marriage Act and other heresies. They are still in a hanging mood.
Nachum, your linked article basically just asks the question, but the comments are very interesting indeed. overall, they agree with denydenydeny - that this is a rejection of her Clintonian associations in a regime purge.
But a couple of comments generalize the concept into a strategy disagreement on the left - whether to pretend to be centrist to get the RINO vote, ala’ Clinton, or whether to stay openly communist and just lie cheat, steal and ram everything though ala’ Obama/Pelosi.
So now, the really odd thing is that Obama went and nominated a Hillaryite. Perhaps he is trying to heal the rift, but Leftists aren’t into healing (despite their endless invocation of the term). Disagree with even the slightest issue with a Leftist, and they want you dead. That’s why they are constantly ripped apart by screaming matches and infighting.
And Hillary’s no healer/centrist. Behind her middle-of-the-road paintjob, no one has taken more scalps out of sheer vindictiveness than she has, and no one is safe from her - Left, Right, Up or Down, Friend or Foe. When you combine that deranged insanity with her endless screwups, no wonder they decamped for Obama.
But now Obama has nominated a Hillaryite, and the screams are echoing across the country! LOL!
Buncha schmucks.