@no1marauder saidAustin's waiver was approved by a wide margin in both Houses of Congress:
There is nothing in the relevant statute mandating that the Congressional waiver may only be given in "extraordinary times".
"The House voted 326-78 on Thursday to pass the waiver exempting Austin, who left the military in 2016, from a law that bars officers from the Defense Department’s top civilian post for seven years after retiring. The Senate swiftly followed with a vote of 69-27."
https://www.msn.com/en-us/news/politics/congress-approves-waiver-for-austin-to-be-defense-secretary/ar-BB1cYwvO