Walzer, like his late colleague Irving Howe, has a divided conscience. They both came out of an environment very similar to neo-conservatives like Kristol and Podhoretz and with age they can't help but be disappointed by younger leftists repeating the same old mistakes, but their left-wing emotional ties and self-identification overpowered their intellectual qualms about leftism.
The neo-conservative parallel suggests the complexity of the problem: to break with irrational and harmful illusions without simply surrendering to power and the hope of exercising it. From the outside, it looks just like another silly conflict between the loony left and the cynical and opportunistic left, but those inside necessarily take it more seriously.