He's got Buchananitis.
Buchanan, despite being a critic of President Bush (and some of it is well deserved), did ultimately support him over Kerry, largely because of judges. And if you actually listen to Buchanan speak of Bush, it is not some full-blown negativity. I get the feeling that Buchanan likes Bush and appreciates his steadfastness (so far) on picking conservative juges, fighting for traditional marriage, etc, but that he simply disagrees on Iraq, free-trade, and immigration; and on the latter he's right as Bush is quite liberal on immigration.
Roberts, on the other hand, seems to genuninely dislike Bush, and I've not seen a single positive word said by him about the President. Now I agree with Roberts on certain and specific issues, but I don't agree with his very dark view of Bush, nor of his apparent view that a Kerry win would not have been so bad (the only thing that will make me think that is if Hillary somehow manages to get elected).