Would you not be able to access whatever higher level of care he recommends? You should get whatever treatment you need for where you're at right now, mental health wise. I know plenty of therapists can work in an outpatient setting with people who have suicidal thoughts that only go so far. If he's not one of those therapists, or if your suicidal ideation is beyond what can be accommodated in a once-weekly outpatient setting, then the ethical thing would be to refer you, not to restrict what you can talk about. It can be hard to see if your thoughts are fuzzy, but if you need more than what he can give you once a week, then you should seek it out elsewhere if at all possible (2-3 times weekly with somebody else, intensive outpatient, etc).