“If we had a list of all the Cruz supporters who guaranteed that Cruz would honor his promise “once Trump is the nominee,” we could ping them after the speech, and ask for feedback.”
Most of them resigned from the site, or got zotted, because they didn’t actually expect Cruz to not win.
I’m sure you’re right where a large quantity of Cruz supporters are concerned. Nevertheless I have been lectured repeatedly, within the past couple of weeks by posters who are still active, that Trump was not the nominee. Once Trump became the nominee, I’ve been told, Cruz’ endorsement would quickly follow.