A popular knock on this second Donald Trump term is that the president stocked his administration with nothing but saluting loyalists. Tell that to the staffers scheming to undercut his signature tax reform—by “managing” him into surrendering to the left’s favorite talking point. A (delighted) mainstream media several weeks ago started writing stories about a new Republican interest in raising taxes on “the rich”—namely hiking the top individual tax rate from 37% to 40%, higher than even under Barack Obama. These reports all come from anonymous White House officials, and always take care to insinuate Mr. Trump is “open” to...