Did the F.B.I. Save Trump’s Presidency?

There has always been a relatively innocent and eminently plausible interpretation for why Donald Trump’s presidential campaign had so many suspicious ties to Russia. Let’s review:

First, the candidate himself took an indulgent view of Vladimir Putin. This was naïve, but it was no crime: Barack Obama also sought rapprochement with Moscow in 2008, despite Russia’s invasion of Georgia that year and the Kremlin’s notorious human-rights abuses.

Second, Trump had extensive business ties to Russians, both as customers and partners. This, too, isn’t criminal, even if some of those customers...