It is the same reason why I believe that any hope of change lies in the conservative right within the Republican party, seeing as they have already managed to push the whole party right and bring up important issues and solutions
Voting the lesser of two evils, especially when you are a rightist, is very important. The main enemy of the right is fascist socialist and totalitarian ideals, and allowing any victory to the Democratic party is going to damage the rights chances of gaining political power in the future. In addition, the current first-past-the-post election system is rigged against 3rd parties. Voting 3rd party or not voting at all are ineffective methods of making change.
Republican supermajority only means that the caucusses in the party become the new parties.