After his fourth indictment, bringing his total count of felony charges to 91, former President Donald J. Trump last week posted a video online accusing President Biden and his family of being criminals. “The Biden crime family,” he claimed, had received millions of dollars from foreign countries. “I believe we have a compromised president,” Mr. Trump said, adding: “He’s a Manchurian candidate. That’s why Crooked Joe is letting other countries walk all over the United States.” For Mr. Trump, outrage is a selective commodity when it comes to presidential families…