I think it a great idea for your brother to get some support as an ex smoker and someone who has worked in the detox industry, coming off THC is really very hard, there are not really many medications out there to assist with detox. It also stays in your system for quite some time, so the coming down/off effects can come and go for longer than you might expect.
I don't know anything about the services there (from OZ) but if they are anything like here, they will take his issues seriously and give him idea how to cope.
IMO nobody should have to detox/rehab on their own, it takes the will of the person and the support of family, friends and healthcare professionals to successfully quit.
Hope all goes well for your brother.
