Because they weren't behaving as their surrounding wanted them to. The reason was given in the article. You don't need to know the birth certificate name of that kid to talk about that.
In fact, the very people asking the most loudly for using this name are the crowd that bullied them alive.
In your earlier reply you said relevancy of something was subjective. No. Inference of facts from given information by each person may be subjective. But the information itself, must never be influenced by the subjectivity stemming from the information provider.
I get that revealing some information which maybe considered sensitive will be used by awful people. But that doesn't apply here. You cannot withhold information on the pretense that it will be used maliciously. Otherwise it's no different that dystopian stories of catching criminals before they commit crime.
This comparison is so lazy it convinced me to step out of this discussion.
Good day.
The Wikipedia article skims over this, instead focusing on the trans and bullying aspects. This will have been a deliberate editorial choice as well.
Instead, like everything else, it's another opinionated aggregator of information.
Any information which is relevant to the subject of article and brings clarity should not be censored, ideally.
Also if you could understand what I'm saying, you would realise I'm not asking to put birth names of every trans person with a wikipedia article in their article. Because it's not relevant.
You keep mentioning "harm" but never exactly describe what harm? What more harm can you imagine for a person who committed suicide due to bullying?