Nate Silver's take is that the White House wants Olympia Snowe's support because a few conservative Democratic Senators may be attached to her, and if you lose her vote you could lose theirs. Maybe. But in that case, why would the White House be more solicitious of her support than Harry Reid is? Reid is going to have a better grip on how his caucus votes than Obama. If he says they can do it without her, they probably can.
If the White House message to Reid was just the "We hope you guys know what you're doing," from Ezra's post, that's all well and good. That is, assuming Reid knows what he's doing. And I'm inclined to think he does, because I can't remember Reid pushing his caucus so hard he lost a vote before.
Update: Matt tweets about how Reid muffed the vote count on the Medicare doctor rates fix. I'd count that as a screwup if I hadn't read Ezra's comment that "This is arguably the best possible outcome for the Democrats: They don't have to pass a bill that increases the deficit, but they get with the docs credit for trying, and the American Medical Association is furious at the Republicans." If Ezra's right about that and the Senate leadership saw it the same way, Reid may have been playing a crafty game against the legislation or (more likely) just not caring much about the outcome. I assure you that we're not seeing either of those with the public option.