I agree, in part. Yes, with a substance abuse disorder, the brain associates the drug with a survival. Without the drug, the brain thinks it cannot survive.
However, the decision to sit in that seat and fly with people in the back is a choice. He could have called in sick. Does he need help? Absolutely. But there are certain things that should be a 'never' event in a career. One of those is flying while intoxicated. To attempt to do so demonstrates a gross lack of judgment that one is impaired, or careless disregard if one is aware of just how impaired one happens to be.
I can have compassion for him as a person, and can have empathy regarding his illness. I struggle to have empathy for his lack of judgement. People with substance abuse disorders often relapse. This could happen again if he's given a second chance.There have to be consequences for this. I don't think he should be able to fly commercially again.