But are the medical needs relevant in this case, where the medical authorities have reached a conclusion that they can provide no further medical treatment and that all medical technical support should be withdrawn? And have withdrawn it.

There is no dispute that the best interests of the child should be paramount. The issue is whether those interests are best judged by the parents or the medico-legal system.
As I indicated, I would argue that it is impossible to reach a firm judgement on that matter - and that in this situation the parents should be the ones to have the choice, rather than this responsibility falling to a judge.