Although I am sympathetic to the criticism (and I think there are some very good points in the second half of the piece), the above (and what followed) - IMHO - sounds a lot like reverse reasoning. The author lists things that (a) those left-of-liberal would rank higher than liberals would, (b) things that Obama has reneged on, tried and failed, or only partially succeeded at. Then he says, ergo, McCain would have been no worse.
And then adds that perhaps he would have been better because Democrats would have been stronger: Dems, he says, could have held out for a “public option”.
Underlying this analysis is the axiom that big money is united and Obama is a tool of big money in the same sense that McCain would have been. But somehow, to this axiom there is the corollary that the Democratic party would rise to represent the people via a public option demand.
This reasoning in my opinion is a more than a bit wishful.
One could go the other way and talk of the Supreme Court nominees that McCain would have appointed (given Senate Democrats's demonstrated willingness to cave on that matter), the full on crazy he might have brought to the war in/on Pakistan, etc.
I think if at all we are to play the comparison game, it would be better to see how Obama would compare to a better liberal - e.g., the FDR mentioned in passing in the article.
2 cents,
—ravi
P.S: It is possible that the Republicans, especially McCain, might have played tougher with Israel (similar to Papa Bush), but Israel/Palestine perhaps is more representative of the liberal/left schism than any other issue. The Democrats that the author starts with - the ones who were united in the belief that McCain was a worse prospect - are at best ambiguous on the issue of Palestine and are less likely than “us” to find Obama’s behaviour problematic.