I don't believe they have outlined the criteria "Biblically drunk" anywhere have they?
I don't remember seeing this in the leaked copies of the Flock book.
On the other hand, they've a fine gradient when it comes to porn and what kinds are disfellowshippable and what kinds are not. It shows where the priorities are.
One elder told me that drunkendess was "hard to prove". And I was like, "What?"
It's one of those things that many elders, "Bethel heavies", Governing Body members, and at least one Watchtower President have been guilty of. And yet...some have been disfellowshipped for it. Hayden Covington comes to mind. But the majority seem to avoid any sort of punishment.