The unwaveringly faulty conventional wisdom of electoral politics told us this week that when the drums of war sound, voters gravitate toward candidates with governing experience. That didn’t work for Hillary Clinton in 2008 with her “3 a.m. phone call,” but some pundits and partisans are arguing that the uncertain reverberations from the liquidation of Iranian Gen. Qassem Soleimani last week will see voters clutching the apron strings of Steady Joe Biden, whose five decades in Washington mark him as the most seasoned potential president on offer.

“I...