My intuitive thought is simply to quit, and start another academic pursuit (assuming you are really interesting in science and research); it could be rather hard, but that is life. LIFE never goes easy.
1. When under an abuser, frequently you internalize their narrative.
2. Allegedly the professor threatened to kill him if he "ruined his reputation."
3. If he was an international student (I do not know if he was), he could quite literally lose his visa for losing his spot in the program.
4. If your advisor hates you and you haven't managed to safely switch advisors, good luck getting a letter for any future academic pursuits. (Unless you're willing to speak out about what happened, or you have someone willing to write an explanatory letter on your behalf.)
5. When you're being abused and threatened with retaliation for speaking out and so on, you aren't thinking rationally. It's really traumatic and scary, and sometimes it's hard to imagine a path out that is tolerable, and death sounds safer and easier.
We in academia need to respond by setting up better systems to recognize and safely escape abusive situations without permanent harm to one's career and mental or physical wellbeing. And also by making those systems known to students and very easy to access and use.