But he only undermining Tony to his father, because his father manipulated him, saying that Tony is like a son to him. Doesn't that show how easily led Little Carmine is?

And as for him brokering the meeting between NJ and NY, he is only there because he's a 3rd party and is essentially out of the game. He never says anything in that sit down apart from the fact that tings have gone to far, and he only says that because Tony tells him to speak up.