Those who have to control him in custody have a right to life. Those people's families have the right not to live in fear. If court dates or the mention of the crime itself is a trigger to violence, self-harm or suicide, would you have the same opinion?
Say he likes to assault staff when triggered by upcoming court dates. He likes to strap his razor blades to toothbrushes to slash their faces. Or maybe he just prefers to walk up behind staff and smack them. Maybe he has mental illnesses or learning difficulties that are yet to be understood or diagnosed that lead to this behaviour. Maybe he likes to throw buckets of poo on staff, or cut himself to the point his cell looks like a murder scene.
If he does this because of upcoming court dates, or the inability to face his crime yet, what do you think his behaviour would be like after sentencing?
There may be a time and a place for that statement to be read to him. Just not now. Not everyone thinks and behaves like you, unfortunately.
Like i said, there will be a very good reason why that decision was taken.