So sorry to hear about this pale.emperor. It's really encouraging to know that your brother reached out to you when he was in despair. It probably sounds scary to be sectioned but right now it's possibly the best thing that could happen. He can talk to his psychiatrist and nurses in complete confidence and he will be able to control who is allowed to visit.
All you can do is what you have done today and be there for him. It's times like this that the WT is exposed for the despicable controlling cult that it is.