I think that is very accurate.
I don't know how subconscious some of this might be (on the part of Mitt or any other leading Republicans) but I think there may be a sense that the country has problems that cannot be fixed. The guy in the Oval Office has a very unenviable job (largely because of the guy who is in the Oval Office). The president from 2013-2017 is going to be in charge of a disaster. Did any Republicans want that responsibility?
One way or another, I think Mitt went a long way in making sure that the Democrat got the post.
(Republicans have made themselves useless, toothless, and clueless.)
FMCDH(BITS)