All above have some good ideas. No one yet has addressed the real issue of the veteran giving bad advice. Any talk to the newbies only helps them and not the next set of victims.
I too hate confrontation, but opening a dialogue with the veteran need not be confrontational. It will have a better chance if the discussion is nonjudgmental but allows all the participants/observers to think things through. An example: Enter the conversation with a question, "The flight deck sure is interesting, but it's a bit deep for recreational divers. How do you deal with the decompression issues and the smallish amount of gas with only an AL80?" or "Sharing a .... is fine as long as everything is going right. I'm curious how you handle a problem without ... if a buddy separation occurs." "I tried that when I was a new diver and had xyz problems, how do you prevent/deal with them?
This approach lets everyone think about the issues without putting anyone, including the veteran, on the defensive.
You have a future in politics!
I agree with the need to have the veteran revisit the decision.
Equally important is to get the new diver to "think like a diver". This is a phenomenon I experieinced as I was getting started in diving and as a scubaboard junkie. You begin to look at situations with more of a risk assesement attitude and think in terms of concequences, liklihood and mitigations. I then found that same mentality spilling over into the rest of my life.
Pete