This sounds exactly right to me.
I don't see how anyone can even argue that executive privilege includes the right not to appear before Congress at all, even to answer questions that clearly are not privileged. Karl Rove, for example, now works as an analyst for Fox News. He holds essentially the same job that Bill O'Reilly does. But if O'Reilly were called to appear before Congress, and he refused to appear on the grounds that he might be asked questions that would require him to, say, disclose the name of a confidential source, he would be laughed out of court -- and ridiculed all over the country. The Bush administration deserves equal ridicule.