Yes, Leon has written movingly against Israeli ultra-nationalism in 1994 and 2002. And many other times before and since. He did it a couple months ago. This idea that he has somehow stopped doing so is an ideologically-charged game of internet telephone. No, he hasn't accepted Peter's sudden belief that all supporters of Israel must focus obsessively on the evils of the Israeli right, at the expense of all other evils. But that's another argument altogether.
But when you read the Diarist cited, you find a somewhat more nuanced view. In so far as it is comprehensible, it is a response to appallingly revanchist behavior by far right settlers, but supports their goal:
The lunatic Jews who insist that a Jew must live anywhere a Jew ever lived do not see that they, too, are re-opening 1948 and the legitimacy of what it established. Why does the Israeli government allow the argument for a unified Jerusalem to be mistaken for the heartless revanchism of these settlers?
So Wieseltier's attack on the far right is that they are weakening the case for Israel's permanent control of all of Jerusalem, and re-opening the entire question of the legitimacy of Israel to boot. TNR's liberal Zionists manage to maintain an admirable distance from the farthest Israeli right, while never supporting anything that might actually prevent them from driving Israel into the ground. Has TNR backed Obama over Netanyahu on the settlements question - about as basic a question if we are ever to get a two-state solution? You need to ask? Matt Zeitlin sees the debate as the tyranny of small differences:
I think there’s a lot of talking past each other from the Chait/Wieseltier/Goldberg wing and the Yglesias/Beinart/Ackerman/Klein wing of the American Jewish punditocracy.
Best I can tell, on matters of actual policy, they mostly agree with each other and stand opposed to the Israeli and American right on the issue. Much of the apparent disagreement seems to stem from different ways of viewing and describing the conflict (the threat from Iran, Hezbollah and Hamas; the legitimacy of Goldstone; varying accounts of moral goodness; how much we should “focus obsessively on the evils of the Israeli right” and so on). There’s also a perception among some people further to the left on matters related to Israel that the TNR/Goldberg are just Commentary style hawks on Israel, which isn’t true and I think Wieseltier’s pieces, especially the 2002 one, show that very well.
The question is whether those pieces are, in fact, outweighed by the larger task of defending anything the Israeli government does at any given moment, and smearing anyone who dare criticize it.