I believe that what drives Rabs, is that he is a Ron Paul man all the way and Palin is an obstacle to Paul as a presidential candidate, social conservatism may play a role also.
That could explain certain behaviors of Ron Paul supporters. Many Ron Paul supporters don’t seem to like many other Republicans. But many of those seem to reserve particular hatred for Palin. Palin is closer to Paul politically than someone like Romney or Huckabee is. Paul’s people really should like Palin more than Romney. But, if Palin is seen as a competitor to Paul - someone who would appeal to limited government types - it makes more sense. Palin might be seen as someone who could take Paul’s votes away, but Romney would not be getting votes from Paul’s limited governement supporters.