Good for him. I can't help but think that Klobuchar nailed him so hard he saw himself as he was, somebody so self important he was entitled to butt in line and the truth of it got to him.
Democracy has been dead for a long time, at least since the time of Carter so regardless of how not electable anybody may feel Sanders is a progressive is the only way back to government of, by, and for the people. Moderates will just compromise until the last nail is driven. Moderates are just voting for suicide by pill rather than by pistol.