I’ll give you four explanations for how this might be true and none of them are “They really said it and really meant it and really thought he might give Trump a run for his money.”
The man is a further-left John Kasich. The only reason to think he’d have meaningfully outperformed Mark Sanford or Bill Weld in a primary is that, as a sitting governor, he would have had a larger media megaphone.
But so what? If anything, his departures from right-wing orthodoxy would have given Trump a bit of extra cover as a “true conservative,” relatively speaking.