There are really only a few theories that work in this situation:

1. He really did get a phone call telling him to hold off.

1a. The phone calls were a threat

1b. The phone call was a legally binding gag order

1c. His editor (Bannon) called and told him to wait because something more official/concrete is pending

1. He never had any intention of talking about Pizzagate, and only used the buzz surrounding it to drive up views on his UofF talk tonight.