He's a rabid right-winger, of course. But he isn't completely without principles like most of the rest of them. And exposing a CIA agent crosses his line:
We have noticed that Valerie Plame Wilson has lived in Washington since 1997. Where she was before that is not disclosed by research facilities at my disposal. But even if she was safe in Washington when the identity of her employer was given out, it does not mean that her outing was without consequence. We do not know what dealings she might have been engaging in which are now interrupted or even made impossible. We do not know whether the countries in which she worked before 1997 could accost her, if she were to visit any of them, confronting her with signed papers that gave untruthful reasons for her previous stay — that she was there only as tourist, or working for a fictitious U.S. company.
The importance of the law against revealing the true professional identity of an agent is advertised by the draconian punishment, under the federal code, for violating it. In the swirl of the Libby affair, one loses sight of the real offense, and it becomes almost inapprehensible what it is that Cheney/Libby/Rove got themselves into. But the sacredness of the law against betraying a clandestine soldier of the republic cannot be slighted.