Ezra seems to be in the same school of thought as I am. It's nice to have some company.
Obama is counting votes, not prosecuting grudges. Lieberman's slingshot into the furthest reaches of the far right was always a sadly transparent reaction to his rejection by the left. Human beings do not enjoy criticism. They gravitate towards affirmation. If he can be flipped yet again, that's a far better outcome from the perspective of passing major pieces of legislation, even if it's not the most "just" outcome from a party perspective.
This, incidentally, is the other side of No Drama Obama: Part of avoiding drama is refusing to make decisions based on your own drama.
Today's vote succeeded in two ways. 1) It whipped up one more vote leading to that coveted 60. And 2) to use a Cuban Missile Crisis analogy, it succeeded in blockading Lieberman rather than bombing him -- it rebuked him without rebuking him. Again, I'd hate to be stuck at 59 in an attempt to break a GOP filibuster -- all because of a scorned and pissed off Lieberman.