But it seems that Trump knew Cruz wasn't going to endorse...
"He didn't ask me to endorse and, indeed, three days ago I talked on the phone with him and told him, ‘I'm not going to endorse you,’" Cruz said, defending his non-endorsement speech.... so it's not as though he lied his way into that speaking slot. But he did choose to take the stage, unlike Rubio — who had a little video just before Cruz's slot — and Kasich — who's nowhere to be seen, even with the convention in his home state.
Cruz's statement that Trump knew in advance there'd be no endorsement is backed up (after the fact) by Trump:
Wow, Ted Cruz got booed off the stage, didn't honor the pledge! I saw his speech two hours early but let him speak anyway. No big deal!— Donald J. Trump (@realDonaldTrump) July 21, 2016
So you have to wonder whether Trump is lying to save face after the fact, whether Trump is easygoing and accepting of a diversity of views — No big deal!* — or whether Trump thought Cruz's sanctimonious on-stage preening would ultimately serve Trump's interests.**
* Says the man who's central concept is the deal.
** Everything seems to ultimately serve Trump's interests. Ever notice?