I think the idea is that Ted is so hard for some people to take that just about anybody would "warm" him up -- or provide a refreshing change.
Certainly, Carly Fiorina's not the "warmest" or sweetest or dearest person in the world, but when she isn't in full-on attack mode, she could soften Ted's sharp edges for some people.
That could be said for a lot of people, though, because those edges can be pretty sharp.
Assuming he gets the nomination, he has to go with somebody with political experience and stature in the party. Carly’s an amateur and makes Cruz look amateurish, and would anybody on the fence really decide to vote for Ted because Carly’s on his ticket?