The press says a lot of things that are wrong. If I were the parents I would invest in a private autopsy being performed.
The family said that their "son/daughter" was subjected to bullying by other students (from the article): "the teen’s family said there was harassment over the teen’s nonbinary identity."
High schools are rough (I worked in one for 33 years) and kids can certainly be cruel, especially against those who stand out in any way. I wouldn't expect it to be easy for a "non-binary" type of student.