Rudi has several things going for him in the primaries:
1) The social conservatives have no viable candidate to support in the primaries. At least none that has a chance of challenging Rudi in terms of war chest or political prestige. Their is no neoconservative or social conservative in the race of any standing who has a chance.
2) The chance of Hillary or Obama beating a weak Republican candidate is going to be a bigger arrow through the heart of most social conservatives than a strong Rudi being their candidate even if he is a liberal Republican.
3) Rudi seems to have the support of characters like Limbaugh and Hannity. I'm not sure why but I suspect because they think he has the best chance of beating the Democrats even if his politics are different from their own. The fact is that both hold huge sway with social conservatives.
4) When it comes down to it I suspect all but the most inane social conservatives would rather trying to twist the arm of a liberal Republican to do their bidding than have to face a Democrat who will ignore or worse work against them.
5) Rudi is viewed as being strong on crime and a wartime leader who is strong in times of crisis.
6) Moderate Republicans are fed up with the neocons and are likely to be a stronger force in the primaries.
The fact is that the polls bear this out. While Rudi's numbers are better with moderate and liberal Republicans he is still in the lead with social conservatives too. When it comes down to it if you don't have a horse that can win the race are you going to go home or are you going to put the money on the horse who can beat your arch enemy. I think everyone understands that if Rudi makes it through the primaries that of all the Republicans he has the best chance of slaying Hillary. The fact that Hillary only loses to Hillary in NY State by 50 to 42 percent indicates just how much he can appeal to even Blue State citizens. He actually ties with Obama in NY in some polls and out distances both him and Edwards in others. The fact that he could make New York competitive says something about his national appeal. When the Democrats have to devote resources to fight for NY State in a national election it isn't a good sign for them.