The last time around, Trump’s efforts to pack the Defense Department with cranks and flunkies came too late to bring the military under his full political control. The president and his advisers were slow-footed and disorganized, and lacked familiarity with Washington politics. They were hindered as well by the courage and professionalism of the military officers and civilian appointees who, side by side, serve in the Defense Department.
… In a second term, Trump would combine his instincts for revenge and self-protection. He would seek not only to get even with an officer corps that he thinks betrayed him, but also to break the military as one of the few institutions able to constrain his attempts to act against the Constitution and the rule of law.
He’s still holding up a lot of other spots by holding those top general slots as well. For the lower promotions to go through, they need the people moving into their top general slots to vacate their positions. And for the even lower ones, they need the lower ones to move up.
Tuberville essentially said that he’s not going to hold up the entire line of people, just a few at the head of the line. But holding up the head of the line means the rest of the line is impacted.