I think you're very wrong here. Fineman is trying to game out the 2008 election, and pondering whether or not Bloomberg will jump in the race. I think he's right on one count--Bloomberg will have to make his mind up relatively early, but other than that, I think he's fairly well off the mark.
Fineman's thesis is based on the idea that what Bloomberg needs is for the two candidates to be shaken out fairly early, so he can then assess the field and see if he can mount a charge. But Bloomberg can be a king-maker of sorts if he wants to.
There's been a lot of talk lately about the split between the business side of the Republican party and the religious wing, and a lot of right-wing pundits have come out and flatly said that Huckabee is unacceptable to them because he's (my words) one of the dirty unwashed. He's from the side of the party that the business cons want votes from, but don't want to have in charge. They're elitists, and the rabble are fighting back. Tim over at Balloon Juice just made a post which details this split.
Here's where Bloomberg comes in. If Huckabee proves that he's more than just a flash in the pan, if he wins in Iowa, Bloomberg can effectively end the Republican nominating process by stepping into the race. He can make that split happen, because he can give business-minded Republicans an option outside the party. They don't have to vote for Clibamawards as the lesser of two evils (from their perspective--I find Clibamawards just fine). They can call themselves the "New Republicans" or something similarly silly, and lay claim to that 20% or so of the population that wants to be Republican but doesn't want to be associated with the preachers and gay-haters.
In fact, it's probably better for Bloomberg if he doesn't wait. He needs to knock out the other contenders to the Republican nomination if he wants to have a shot at the big ring--there has to be a clear difference between him and the Republican nominee, and Huckabee is the guy in that case. There's not enough difference between Bloomberg and Romney, or Bloomberg and Giuliani to play up that politics of contrast.
On the other side, Bloomberg has to hope for an Edwards or Obama win, and to my mind, the former is better for him, again because of the contrast. You can never underestimate the power of racism, but the rhetoric coming from Edwards (rhetoric I applaud, by the way) is that of class, and Bloomberg's natural constituency is of the moneyed elites and those who think they're of the moneyed elite, even though they're not. He won't be able to play the contrast game with Clinton--she's as business friendly as he is, and the Hillary-hate game will solidify an otherwise lukewarm progressive movement behind her.
So if that happens--Huckabee and Edwards/Obama win in Iowa--expect the Bloomberg noise to start. And if Huckabee turns an Iowa win into a better-than-expected New Hampshire showing and a South Carolina win, I'd be shocked if Bloomberg isn't in the race.
Which is fine with me. I like the Democratic chances in a head-on race with the Republicans. I like them even better with a divided field.