This.
The intent wasn't transphobic.
The victim was more vulnerable because of comorbid issues (which probably were compounded by being trans).
This in turn gave the killers more opportunity to carry out their actions.
And the language was about the killers dehumanising and processing based on how they identified with (or more accurately differentiated from) the victim. Any of the potential victims would have been othered in a similar way based on their identity traits. The issue is that trans as an identity is so politically sensitive that it BECOMES the story and it's is then is ASSUMED to be the intent. Even though it's not the driving motivation.
So trans is relevant in terms of social isolation and appalling dehumanisation by it but it's NOT The Singular Why.
Social isolation is key to this case - and you can't get away from three points. The chicken and egg argument and whether social transition may make social isolation worse and whether adequate mental health support was available or perhaps dismissed due to trans identity.
It's an uncomfortable discussion which can go multiple ways particularly for those with a rigid agenda.
If comorbidities are present that raises questions of the value of transition and whether it's seen as a magic bullet. Especially if autism is a driving factor fueled by the social isolation it brings. The idea of transition is rooted in the idea of conformity and fitting into gendered roles better - but if being trans actually alienates you from both sexes it might actually cause more social isolation and less ability to fit in. The TRA argument is that we should just accept people for who they are not what they are - but this doesn't actually solve the internal knowledge of difference anyway, so you can't necessarily just dismiss 'being different' as an external force (which may come in the form of transphobia). And social isolation might be being driven from internal feelings rather than external forces. If there isn't proper support for this (which goes beyond communal shouting transphobia at everyone) you still have an issue.
I'll give this as an example. Family alienation is common for trans people. But back in the day when this was kicking off in my family, there was a slightly different understanding of it being promoted by charities. This was just at the tipping point of where it began to be radicalised and I think think it got ignored by my family because of that radicalisation. It's something I remember well.
The advice my brother had was that many families reject their trans member but it acknowledged the reverse is also true. Many trans people actively distanced themselves from family because they were the biggest reminder of what they weren't - so they rejected their family. My brother was so primed for rejection he lashed out in spite of efforts made to try and accept and his behaviour made it ultimately fulfilling (his partner at the time was rejected so there was masses of projection going on there and honestly it was a really unhealthy dynamic to the point I'd call it abusive).
I ultimately feel that there had to be someone to blame and I was it because DH and I were too much of a reminder (seeing my brother dressed up was like looking in a broken twisted mirror - I wonder what the reverse was like for my brother. And DH fitted the stereotypes of an alpha male perfectly. He was the perfect son in law - the son my dad had 'always wanted' for want of a better way to phrase it)
But you can't ever run away from yourself and it's still always there in the back of your head. It's a demon nagging - "is it cos Im trans?" It becomes the catch all explanation rather than learning to understand social cues better or be more self aware of the impact of your own manner. And this in turn is placed as a one size fits all template for understanding all other trans people and the situations they are in.
It is the removal of all nuance.
So social isolation may be inescapable for some and be made worse by trans. Especially in the cauldron of radicalisation and lack of proper access to appropriate mental health services or social skills support (particularly for those who are autistic).
There are arguments that transphobia drives the mental health issues, thus if you end transphobia (an external force) you end those issues. I really don't buy into this because it's too simplistic - internal forces remain - which activists really don't want to properly discuss and address because this is much more difficult and hugely complex.
The CASS report highlights how homophobia, trauma, autism and sexual abuse were conveniently swept under the carpet by the Tavistock and dismissed in this way by cries of transphobia. Gender dysphoria exists and people are attacked for transphobic reasons BUT the how and why of what's going on underneath still matter otherwise you risk doing more harm. These kids are more vulnerable even without trans.
If we want to do the best for kids who are trans identifying we need to talk about both the external and internal forces at play, how they interact and how may be present at one point but the other more relevant to that particular situation (and the converse true at other times).
Its a hard deeply complex thing and trying to reduce it into 'a magic bullet' simplexity does everyone a massive disservice.