Democrats are struggling over the direction of their party, and this week things got more complicated. In addition to the splits over the Green Leap Forward, Medicare for All and constitutional rewrites, Robert Mueller’s report has opened a new divide. It’s Team Reality vs. Team Bitter Enders.

Granted, the end of the special counsel’s probe is a shattering blow to Trump haters. So long as Mr. Mueller continued his investigation, the left and its media mates were free to spin collusion claims and nurse hopes of a toppled Trump...