Something predictable happens in “Assassination Run,” the fourth-season finale of The Boys: The megalomaniacal superhero Homelander takes over the U.S. government. The details of how he does this — through a coup on January 6, with “patriots” supporting him and a televised speech in which he promises that under his leadership, “America will be safe again” — are representative of the kind of dull-blade political satire to which this series has increasingly turned. Over time...