Let’s be honest. Any social norms about when drinking is socially acceptable go out the window at airports. It’s been that way as long as I can remember. But Ryan Air/Spirit/frontier passengers all kind of self select for having a miserable experience so I don’t blame them for trying to numb the pain.
As someone who recently got day drunk at an airport, the reason was I had to fall asleep at noon or I was going to be far too jet lagged. 12 hour time shifting is an absolute bitch