It’s no crime to acknowledge that natural gas reduces carbon-dioxide emissions, though Mr. Steyer’s green collaborators uniformly oppose fracking. The billionaire, aware of this liability, has of late made some tougher criticisms of gas drilling but has hardly ruled it out—as he has other “dirty” energy.

Is he still invested in natural gas? Have White House attacks on coal and Keystone made those investments more profitable? We don’t know because beyond the July divestment promise, Mr. Steyer hasn’t specified where his money sits (including whether it sits in renewable projects reaping taxpayer subsidies). Turns out Mr. Steyer isn’t very “transparent” about his finances. Attempts to reach him for comment were unsuccessful.

All of this has furthered green suspicions that Mr. Steyer is motivated by more than climate. He basked in the local attention he gained from California ballot-measure fights to keep the state’s climate program in place, and to hit out-of-state businesses with new taxes to finance clean-energy projects. He gave up his Farallon job as he was being mooted as a possible Obama energy secretary. He’s suggested a run for the California governor’s mansion. That might once have been a long shot. But his pipeline campaign, and pledge to spend $100 million in this midterm election, has gained him a national profile. Keystone has provided a pretty good political return on investment.