I'm sure you're going to get a lot of positive advice and compliments on the selfless and generous way you describe you are handling this. I'm going to paint a slightly different picture because I think its important to be aware of the other side.

This issue isn't being handled properly.

Do you actually know what the proper procedure is for the chain of command and the military with a soldier in this position. Your argument that the current response is inadequate will be stronger knowing this.

We need to help out brothers

Correct, but we need to treat them as brothers not as children. In this vein we need to understand the limitations of what we can do. Unrealistic expectations by us, or worse, unrealistic promises to those in need are actually detrimental if we are unable to follow through.

The problem you also have is that being in the Reserves your ability to manage the situation is limited. Firstly, in that you don't have recourse that would be open to a Regular unit - restricting the unit to the block, constant supervision or monitoring, and the recourse to compulsion if they are resisting or unable to motivate themselves to get treatment. Secondly, as per the previous point, going beyond the official military guidelines, will leave this solely in your hands, do you have the resources (time and money) to take this onboard.

Finally on this point, while not in uniform, this person can do what they like, if as you say he continues down this path, what can you really do to stop them? This is a slighty bitter pill to swallow. I had a soldier who tried to commit suicide twice in a brief period of time. There was very little, we as non mental health professionals could do. He needed, and was helped greatly by, a short stay in a mental health facility.

"But I want him gone"

Sadly, this may in fact be the correct course of action. The important caveat here of course, is what happens after their service is no longer required.

Good luck, and good luck to your squad member.