It’s kind of weird.
They have seen Don Sr. and also Don Jr. in action before. They disagree with the politics of Don Sr and Don Jr. THEREFORE they have the opinion that both of these men are blithering idiots.
They invite Don Jr. on their show with the intention of humiliating the blithering idiot and destroying him with their superior skills of political debate.
But they discover he may not be as dumb as they think.
Which does not cause them to question their own political views. It just causes them to hate all Trumps even more.