In a just world, his role in bringing Sarah Palin to the national stage would be a millstone around William Kristol’s neck, sinking at last whatever remains of his credibility as a commentator. And the justice would be poetic — Kristol is, of course, the son of Irving Kristol, but he first came to national prominence as “Dan Quayle’s brain.” A lightweight brought him in — wouldn’t it be nice to see a lightweight usher him out …