My guess is that these anti-Rudy folks think that if they can cut everyone else down - then Alan Keyes or John Cox or someone of that ilk will be all that's left. But what they cannot understand is that McCain is who will be left. They are, in essence, working for McCain as they tear all the supposedly *impure* candidates down.
They are not really anti rudy. They simply want a candidate pure as the wind driven snow, and hard right. Something we all want. The difference is that they will not support anyone else, the Presidency be damned.
I'll take McCain any day over Rudy.