And is the insinuation here that there's something wrong with being white or Christian? That whites and Christians are a rather unattractive and robotically single-minded bunch?
Strawman. Dean insinuated nothing of the sort. He noted that he himself was white and Christian, so I don't think his intention was to rip on himself.
The problem isn't the white/Christian aspect of it; the problem is that the GOP is overwhelmingly homogenous, and they intend to keep it that way, in spite of what they might say to the contrary. And what's aggravating is they then have the temerity to claim that they are a big-tent, inclusive party. I call BS.

No, he did imply such a thing (of course, since he is an "enlightened" liberal, he is exempt from such criticism). Just as lefties accuse Republicans of using "code words", the left uses uses jargon to paint the entire GOP flock as bible-thumping fundies. That in and of itself is an offensive characterization, but is also false and misleading. Bush's minority outreach is something that is pretty bold in scope, and (rather than pandering and misrepresentation of the other side), it is an example of trying to find common ground with blacks and Hispanics. The Democrats are terrified that two of their core constituencies might be persuaded to switch to the GOP, and are responding with vicious rhetoric instead of substantive proposals.