Not too surprised. I can't see why Lieberman should feel obliged to support a party that already kicked him out?
No one "kicked him out". We have something called a democracy, where the voters decide who they want representing them. They chose another candidate over Lieberman in the 2006 election. The election was fair and square.It certainly was, but it was also not particularly important either. Losing the support of his party was an inconvenience of course, because it made things just a little harder for him, but ultimately the party banner that anybody of his political seniority runs under shouldn't matter a great deal. The general election results proved this, more or less.
Lieberman now owes the Democratic party absolutely nothing. In fact, the party owes
him a great deal, for permitting them to form a majority in the current Senate.