IF, and it's a big if, Rudy is the nominee, you are faced with a choice, allowing Hillary to be elected POTUS or not. It is the same choice that would have if the nominee is Romney, McCain or Thompson.
I have major differences with McCain, but when presented with the choice, it's no contest.
I will do whatever I have to do, work on any campaign, that will derail Hillary. See, my country trumps my sanctimony. Principle/ idealism, has to give way to reality.
Refusing to vote or voting third party, and allowing Hillary to be elected POTUS is irresponsible, imho.
My problem is that I believe that Rudy will be as bad for the country as Hillary. In addition, if he wins the nomination and wins, the core principles that he opposes will no longer be of any use to the Republican Party. So his victory is more damaging.