The question is, what does Romney fear more: Trump losing and giving Biden/Harris 4 more years, or Trump winning? I believe he doesn’t like either outcome, but which does he think is worse? If Trump is the nominee and Romney never says anything for or against either candidate all through the campaign, that means he prefers a Biden win.
Many might find it hard to believe, but Romney endorsing Trump could be the difference between him winning and losing. I think a Romney endorsement of Trump, with heavy attacks on Biden, would carry weight with the more RINOish Republican voters. If Romney says nothing next year, that will tell us he doesn’t want to possibly put Trump over the top.
Mitt Romney would endorse Biden over Trump in my mind.