The son is not a child anymore.
Just my opinion. I see a lot of people (young adults) who cannot handle things because their parents are constantly doing it for them. This has nothing to do with the mental and physical health here - he has a therapist and if he wants his father to change - then, in my opinion, the support should go to helping son talk to father - not having mother triangulate and demand at this point in time that father be different based upon one upset conversation with son. Or even 2 upset conversations with son. Children have different relationships with each parent. The other parent interfering and giving their spouse orders on how to interact is just not something I see as productive. Father is not abusive that I have seen. Son has chosen to go to father for specific situations that father handled.