Getting rid of Comey removes the guy who is running the Russia investigation. It removes the guy who can look Congress in the eye and say credibly that the FBI is investigating whether anyone in the Trump orbit was actively working with the Russians. It removes the guy who, in February, reportedly refused the White House’s request to publicly knock down stories about Trump and Russia while congressmen in key positions of investigatory responsibility allegedly complied. It removes the one person of stature (figurative as well as literal) in the government whom everyone knows will–even when he’s wrong–do what he thinks is the right thing and damn the torpedos. It removes, in other words, the essential person for a credible investigation.