New Year’s Eve fireworks are over, but things were still exploding on the Morning Joe set today. Namely, the collective heads of the panel members. An episode of mass hysteria broke out over President Trump’s tweet that warned Kim Jong Un, in response to his threat, that Trump has a “much bigger and more powerful” button than Kim’s, and that “my button works.” First up was Mike Barnicle, who fretted over Trump’s “stability.” Next was John Heilemann, describing Trump as “demented and deranged.” Not to be outdone, Jon Meacham diagnosed Trump with a “narcissistic disorder,” while calling for an “intervention“—a...