This week’s U.S.-led Peace to Prosperity conference in Bahrain on the Palestinian economy will likely be attended by seven Arab states—a clear rebuke to foreign-policy experts who said that recognizing Jerusalem as Israel’s capital and the Golan Heights as Israeli territory would alienate the Arab world. Sunni Arab states are lending legitimacy to the Trump administration’s plan, making it all the more notable that the Palestinian Authority itself refuses to participate.

The conference’s only agenda is improving the Palestinian...