These things were requested by the defence. Aviello was summoned by the defence. He wouldn't have ever entered the trial unless the defence and Hellmann had not drawn him into it.
But once he is in, he should not be thrown out arbitrarily, such as Hellmann did, without allowing him to be questioned completely: all those who want to ask any questions to the witness must be allowed to do so. The prosecution was prevented from completing their questioning in 2011 this is is why the hearing of Aviello is allowed now. There was something incomplete. This point is due procedure.
The further DNA test on the 'i' trace is the same. The knife must be tested, because the original ordnance ordered a retesting of the knife, which was not completed. (btw, the defence agrees to this).
So this is due procedure too. The completing of a previous legal procedure.
The photos were accepted because they are just forensic photos, that is documentation from the investigation. Hence they can be allowed.
But the other requests, are not due process. The judge would need a compelling reason to re-open an evidence discussion session on a topic. The defence could not offer any legitimate or compelling reason.