While I fall into the camp who believe he deserves to be thrown out, I'm surprised by some of the reactions, especially all those saying that they couldn't trust him in an aircraft and how he might have put lives in danger.
I like beer (in fact, I'm having one now). Sometimes I drink a lot of it until I fall over. Never, at any point in my career, have I been tempted to drink heavily then go flying viciously hungover, or to fly when directly under the influence. I know where the line is and I stick to it; and had I ever crossed it and been caught, I would expect the appropriate punishment.
This guy likes (liked?) cocaine. He used it of an evening, at least once and bragged about other occasions. Why does that suddenly mean he was likely to be flying while affected by it or the after effects of it?
Liking a glass of wine doesn't make you an alcoholic who's unable to work. Similarly, using drugs, even class A ones, doesn't make you an addict who needs it to get going in the morning.
It does make you someone perhaps prone to reckless or stupid decisions, it does cast aspersions on your character, and it does make you incompatible with service and holding a commission. None of that's in doubt. I can't make the connection though, that using a socially-unacceptable drug (at least a socially unacceptable in the military one) means you can't control your intake or use of it.