Hi and welcome to Sober Recovery
I think the best thing about rehab is that it would jump start his recovery.He'd get some supervised and safe clean time,and also some tools to work towards getting better.It's a long hard road any way you go about it.Meetings can be very helpful.But if he has real difficulty getting and staying clean, rehab may be a good investment.Better a month off work than the long slow descent into hell,with maybe no return.Ultimately it has to be his decision though,and he will have to be willing to work hard.You may want to post on the Nar Anon forum,so you can get the support from people who have been in your shoes.Good luck and take care.
phoenix