It's not that easy when you consider that suicide is such a major part of human culture. I mean, some of the most well known works of literature involve it - imagine a chatbot that refused to discuss "Romeo and Juliet" because it would be unable to do so without explicit discussion of suicide.

Obviously you don't want chatbots encouraging people to actually commit suicide. But by the virtue of how this tech works, you can't really prevent that without blocking huge swaths of perfectly legitimate discourse.