Just in case you come up against cases like this, Twitter has an option to contact them directly and a human will look into the tweet, they work with clinical folks and law on prevention, they do act very quickly - here are the guidelines - https://support.twitter.com/articles/20170313 --- Dealing with Self-Harm and Suicide
If you or someone you know is at risk of self-harm or suicide, you should seek help as soon as possible by contacting agencies specializing in crisis intervention and suicide prevention. Also alert the team devoted to handling threats of self-harm or suicide if you encounter such threats on Twitter.
Twitter’s Approach to Self-Harm and Suicide Threats
After we assess a report of self-harm or suicide, Twitter will contact the reported user and let him or her know that someone who cares about them identified that they might be at risk. We will provide the reported user with available online and hotline resources and encourage them to seek help.