Yes, I agree. It would have to come with the contention that there wouldn't be an arrest, punishment, etc, or that any confiscation would have a limited term. Perhaps someone, in their moment of clarity, would understand that confiscation is the best solution at the time. I think it's at least worth a trial run.

Also, I believe mental health professionals are allowed to report incidents where the patient has indicated they plan on committing a violent crime.