First, I want to agree with you that suicide is often caused by clinical depression or other factors largely out of the control of the victim. Second, I want to agree that depression is often caused (at least in part) by physiological as well as spiritual and psychological conditions. Third, we should not be in the position of giving personal advice whether pastoral or medical.
To everyone else, please be aware that more people will read your answers than you will ever meet. Most readers will find your answer via Google who may very well be struggling with various issues that share keywords with our questions. On a regular basis we see people post answers which are cries for help or rants against how Christianity has hurt them or their family. These folks exist and are quietly watching us, so we need to be careful about how we treat questions that are likely to touch these nerves.
Clinical depression is a medical condition that can, for some people, be treated with medication. When a close family member was diagnosed with depression, I discovered that many of my friends at church are also struggling with the condition. Some have not responded to any medication. Suicide is one extreme response to untreated (or untreatable) depression. Were I to be grieving for a victim of suicide, I would hope that I could find sympathy on a site with Christianity in it's name.
However, we can take this responsibility too far. We can't solve, or even address, all the baggage people bring with them to our site. We need to be sensitive to such baggage, but we can't be crippled by it. Our site is (or ought to be) a place where academic questions of Christianity are asked and answered. Our model is not a church or a support group, but a university department. We must cater to our students and instructors, not the people who sit in the back auditing the class. A religious studies professor might mention that students with depression ought to seek help, but they can't be expected to take class time to deal with that tangential issue fully. No doubt, they would refer students to the school's counseling structure instead.
If you find yourself in TRiG's position, I recommend you provide an answer that communicates your concern. Then, if you still feel other answers (inadvertently) give dangerous advice, you might provide comments to that effect. In any case, a post to meta and/or a mention on our chat room is always a good idea when you see something going wrong on the site.