The most disappointing part isn’t him calling for new taxes, which is supposed to be anathema to Republicans.

The most disappointing part is that the best he could do by way of an insult was “AmazonWashingtonPost.” This is the guy who destroyed Jeb Bush with “low energy.” What happened?

The #AmazonWashingtonPost, sometimes referred to as the guardian of Amazon not paying internet taxes (which they should) is FAKE NEWS! — Donald J. Trump (@realDonaldTrump) June 28, 2017

I don’t know what he means by “Internet taxes” and, frankly, I don’t know if he knows what he means. If he means state sales tax, good news — Amazon now collects that in every state that requires it, as millions upon millions of Americans are reminded daily. In fact, Amazon has been A-OK with taxes on e-commerce for years. It’s a useful barrier to entry for smaller competitors: As a behemoth with universal brand recognition, Amazon can bear the compliance costs easily. A fledgling company can’t. Ironically, the more regulation Trump tries to pile on Amazon as revenge for WaPo’s negative coverage, the more he may end up helping Jeff Bezos by making it that much harder for potential rivals to survive. That’s a weird impulse for a president who’s made deregulation a key initiative in his first five months in office but never underestimate Trump’s ability to wound himself for the sake of wounding a political enemy. (See, e.g., Comey, James.)

Then again, no one takes him seriously anymore when he pops off on Twitter:

The president threatens punitive taxes against a richly valued company and it's barely a blip in the pre-market noise. $AMZN pic.twitter.com/ZlFCTDc0a8 — Brandt (@UrbanAchievr) June 28, 2017

Trump threatened Bezos and Amazon more than once on the trail last year over WaPo’s coverage, most famously on Hannity’s show when he vowed that “we can’t let him get away with” supposedly using the Post to propagandize against taxing Amazon. Meanwhile, eight days ago, he welcomed Bezos to the White House for a summit of tech titans. His mood shifts with the tides and now everyone knows it, including investors who used to be on edge waiting for the morning Trump tweet to know which companies’ shares they should sell that day. No worries this time — at least about taxes — as no one expects a Republican Congress to try to squeeze more revenue out of a major corporation.

What Bezos maybe should worry about is the fact that Amazon’s purchase of Whole Foods requires government antitrust approval. That would be an interesting political dilemma for Trump. If his administration blocks the deal, his feud with Bezos will have set him up to be accused, credibly, of using the federal government to exact revenge on a businessman he dislikes for personal reasons. That’s banana-republic material. But blocking the deal could also be sold, credibly, as a principled populist move to prevent further consolidation of commercial power by a company with already massive influence. Even some liberals might pause before hitting Trump too hard for aggressive antitrust policing. What does the White House do?