Torn in between the two!!

My boyfriend's parents called me lastnight practically begging me to help them straighten out his pot 'addiction'. My man is the type of guy that doesn't like to be told what to do or how to live. On one side I understand my boyfriend completely but then again I also completely see where his parents are coming from. And another thing is that when he gets mad, he curses his mom very badly. He doesn't mean what he says, he just speaks out of anger. But I don't want to take sides because his parents probably would dissapprove of me if I agree with him living his life like this but also on the other side he doesn't like to be told what to do and will get angry with me. He understands we are just trying to help, but he wants to live how he has his mind set. So I guess I have a few questions I would like to be answered.
1. What could I possilbly say to him to let him know I am worried about him, without sounding like his parents?
2. How can I help him have a little more of an open mind to others advice?
3. What can I talk to him about that could make him change for the better, and a change that his parents can see?
4.How can you persuade someone who does not like to take advice?
EVERY BIT OF ADVICE IS APPRECIATED. THANX!

Maybe its the pot that's making him all crazy (meaning cussing and getting very angry).
1. Does his friends do pot, if not maybe it'll be better coming from his friends. You know how it is, if mommy tells me something-she doesn't know what she's talking about but if my buddy tells me the same thing-well maybe I'll listen. You should be able just to talk to him but reading what you wrote, it sounds as if he's hot-headed and dont take critism well.

2. sounds like this guys needs a wake up call. It may not be enough just to talk if he's an addict like you say. Something is going to have to happen to him for an eye-opener. Whether it happens on its on or whether you manipulate the situation.

3. This may p*ss him off-but video tape him when he's acting like an as*h*le. When he is his normal less pot addict self- show it to him. Show him how mean and an as*h*le he is. That woman gave him birth there's no reason for him to be cussing her out. Or you and his parents get together, role-play, cuss his momma out in front of him- if he's a man he should get mad at you. Then you can say 'If you won't respect her why should I?'

4. Well in general, if a person does not like to take adivce, then when giving advice you have to make them think its their idea.

Now here's advice for YOU: If this guy is as bad as my imagination is letting me to believe, maybe you guys should just become friends. Because in LIFE everybody gets told what to do...does he hold a job? Unless he's Donald Trumps son, he's going to get told all the time. And if he has a problem with authority...then you don't want a man that can't take care of his family. If you got to pot head making the family decision, paying the bills, keeping the books, planning the future with no imput from anyone at all...you're DOOMED!