My son has aspergers and the religion was a huge stresser for him. Being out of organisation has greatly improved his mental well being and I hope the same will be true for your brother. My son was protected in the main because his Dad and I acted as a buffer between my son and the elders. He has adapted to the change and now sees the break from the JWs as a very positive thing.
I found the best approach for Kes was not to rush him and give him space and reassurance so he could find his way. I made sure that key people such as his school teacher and carers were aware of the situation so they could support him as well.
If his carers are JWs then they may do more harm than good continuing in the role. New carers who put their role first rather than a religious edict may be more helpful whilst your brother is in this stressful transition period.