To be truthful, I do not no how much or little the dm's drink. I don't usually hang around with them all night, but I know I see some dm's drink a few beers after work. I think you are trying to make more of it then it needs to be.
It wasn't me that said they hoped they could get the guys to go drinking or that it wouldn't be any difficulty to get one particular guy to go drinking.
A beer after work is one thing. Going drinking is another thing altogether. I would think you would know that. I don't think I'm making more of what has been written here.
Some of you may be just fine with this. I'd prefer that the DMs/captains I dive with do not "go drinking" when I'm going out with them the next day.