He trashed Trump relentlessly from the time Cruz was knocked out until a few days before the election. Did he say "go vote for Hillary"? No. Did he rail about Trump being a populist and how bad that was, how his mention of tarrifs would destroy the economy, etc? Yup, every night and relentlessly. And during that time, what was his criticism of Hillary? Crickets.
I'm glad he had some sort of road to Damascus conversion but it came after the election.
Levin announced on September 6, 2016—two months before the November 8 election—that he would vote for Trump over Hillary. That’s hardly “last minute.”