When he’s not solving America’s gun problem, CNN host Piers Morgan spends an extraordinary amount of time battling his critics (there are many) and defending his journalistic integrity. In the course of doing the former, he frequently damages the latter. Because random Twitter trolls, long-time adversaries, and politically disagreeable guests on Piers Morgan Tonight are dismissed as hacks, morons, and scumbags. When I recently criticized him for trivializing the gun-control debate by arguing with unserious people on a very serious topic, Morgan responded with the grace and dignity befitting a CNN journalist: he called me a “poisonous little twerp” on...