Last weekend the Washington Post changed an appalling headline after readers expressed their disappointment. But the paper’s bizarre obituary for terrorist Abu Bakr al-Baghdadi may still need a rewrite.

The original Sunday morning headline on the Post’s website said: “Abu Bakr al-Baghdadi, austere religious scholar at helm of Islamic State, dies at 48.” On social media a wave of satirical headlines soon followed with various Twitter users pretending to announce the passing of the noted vegetarian Adolf Hitler, among other...