I disagree with that actually.
At some point in coming to terms with the violent death of someone, many people go down the route of wanting to prevent history repeating itself.
Guns is one angle to this but the reasons about what drove someone to kill are also going to be part of that conversation.
If it turns out that extremism of any kind is relevant then that's going to be relevant.
If it turns out that access to mental health support is relevant that too is something that's going to be in play.
If being trans affirmative has actively blocked exploring comorbid mental health issues then that's relevant.
If females taking testosterone is a factor then maybe you'd look into that and whether testosterone plus gun purchase is ok.
There's a lot of angles where, a few years down the line, families and friends trying to deal with what happened try to make sense of things in a positive/ productive way as there's no other way to give their child's life meaning.
Certainly I think about how Colin Parry in Warrington, then went on to found the peace centre and campaign for peace / stop extremism after the murder of his son Tim by the IRA thirty years ago. He is still doing so.
So yes I do think the who, why, what really matters to people who have lost loved ones.