My take on this (and may be wrong) is Romney believes Trump is a one-off (which he is) but Romney believes he (Romney) will ultimately be shown in history as being in the right in contrast to Trump and all his “misguided” supporters.
Romney is positioning himself for what he thinks things will be like post-Trump. Romney is on board with the democrat and RINO crowd that will airbrush out Trump’s role in history as if Trump did not even exist. These people will erase everything Trump did once he is gone. Wall? They will tear it down. They will make a spectacle about it like the Berlin wall coming down.
Definitely possible!