From a sentencing point of view, this case is actually entirely predictable. He will almost certainly be the first person ever to be sentenced to life without parole or, at least, an extraordinarily long non-parole period. Really I am not sure that society's objectives (i.e. preservation of order, maintenance of justice, and general/specific deterrence) are well served by the massive sideshow of a sentencing exercise of dragging him into court in the current climate. He doesn't give a crap one way or another about the victims or their families and nothing they say will meaningfully change him or the material facts of the case.
The families giving impact statements is NOT about him, it's about the victims confronting the person who did so much harm and their telling of that harm. It will be part of the healing process for the victims and their families. It is essential that the victims, the families, friends and community get their say, to deny them would be incredibly insensitive and wrong.
He must be given preventative detention with no chance of parole. He must be told that everyone he knows will slowly die and he will not be able to attend the funerals, and that eventually everyone he knew will have forgotten him and that he will die, in prison, alone.