Well, to me it’s pretty simple. When H. asks him if he’ll accept the outcome “if he loses”, it’s tantamount to asking him if he concedes the election, on the spot, in psychological terms. It’s a ploy. So he he says wait and see, i.e. “No, I’m not conceding”, and then they go nuts. Hopefully this redounds in his favor.
And remember when Chris Wallace asked Illary if she’d accept a loss and concede?
Oh, that’s right...