This is my theory as well. Two reasons. One is that on the 5th, Trump released a statement saying that he and Pence were on the same page on what would happen the next day. Second is that in his speech, Trump said that it would take courage to make the right decision, but even more courage to make the wrong one. Imagine what it takes to have to stab the President in the back at his behest and be considered to be like Judas by the base until the truth came out.