Daas you specific answers to my objections are completely undone by your last statement.
“Lest anyone think that I am advocating young bochurim getting dangerously drunk, I am not. I am merely pointing out the weakness of these arguments.”
I love the disclaimer at the end. it belies your your true feeling that somehow you too are uncomfortable with the drinking going on.
PS can anyone please cite the source that it is a mitzvah (from the word tzavaah meaning commandment)? You have what may be at best a d’rabbanan. Im not sure of even that.