A national crisis became a partisan one, leaving the door open to future threats. The fourth anniversary of the Jan. 6 insurrection is a strange one. Had a Democrat won the White House in November, there would be widespread concerns about another siege of the U.S. Capitol on Monday. That anxiety has ebbed only because the chief culprit of that riot is returning to office. In other words, this anniversary reveals less about what the country may have learned about the fragility of democracy than