Regulators no longer have to worry that Spirit Airlines might upset the market by merging with the wrong competitor. The defunct airline made poor business decisions and had to cope with tough circumstances. But if its demise were an Agatha Christie mystery, the fingerprints of Biden antitrust officials would be all over the scene. These antitrust zealots fought a proposed deal between JetBlue and Spirit, and congratulated themselves on a 2024 court victory that doomed Spirit. This was wanton economic destruction masquerading as antitrust enforcement. Sen. Elizabeth Warren exemplifies the perversity.…