Check the rest of the story. COL Yeager was being a fighter jock, drinking with LTs and CPTs and generally setting a bad example for his subordinates. He was a hero so he couldn't be busted out or passed over for it. So the AF promoted him.
In all fairness, it has not been that long since drinking with the guys was not only acceptable. it was required. That did not change until the early 80s.

I can tell you that a Prop Blast at Fort Bragg or a Friday afternoon happy hour on the Yadkin Road O Club annex was a different world.

Tom