Here’s how I read it:
At the outset, the group is hopelessly lost in the wilderness and faced with the prospect of sickness and eventual death (i.e., the present health care system). Because they are strained, angry and unable to agree on even a desperate compromise plan (i.e., the Progressive Blogosphere in disarray), one of them goes insane and proposes the utterly irrational scheme of building a snowman (i.e., joining forces with the Teabaggers, running Patty Hearst against Obama in the 2012 primary).
The “snowman” is a protean concept that can be whatever you want it to be (classical populism, David Bowie, Legos), but in the end does nothing to alleviate sickness and death (paralyzed three-party Congress, Dayquil, sweat lodges), and is eventually destroyed by a deranged man with a pickax (unsustainable alliances with ideological rivals, the CERN supercollider, asteroid Apophis).
The second time the insane individual proposes building a different snowman (December 2010), another deranged man shoots him in the head (historical forces, permanent Conservative majority, unpaid hosting bills, salaried gig as the replacement for Juan Williams on the Fox All-Stars).
Hope that helps.