This isn't one isolated incident. It's many. From many different sources. Including the guy's freakin' mom. Hell, he's admitted to the drinking and banging the one chick who was at the hotel with her family. He's a wreck.
This is the SecDef. We don't need a guy who can't handle his liquor, has PTSD, and has no relevant experience running a large organization or instituting change in one. It's more than just having an idea "hey, this needs to change"-- it's having the ability, knowledge, and experience to accomplish the change while still running the 3 million + person organization.