We’re not talking about silence regarding your own role in an accident. We’re talking about silence while you know that someone could be dying just over yonder and you’re refusing to say anything to let people know someone is seriously injured.
In a situation such as that, it is letting someone die unnecessarily.
Hold on for a tick, this might change everything.
If this man knew of injuries, esp. critical ones, and said nothing -- and IF THE COPS DID NOT KNOW OF THEM -- then this guy would definitely be guilty of the Good Samaritan laws that have popped up everywhere, including California.
However, it should not factor into a Vehicular Homicide case. Only his driving actions should be introduced to demonstrate 'depraved indifference to human life'.... NOT his failure to speak...... otherwise this becomes a very ugly precedent.
You'd have to prove a requirement to not only act, but provide supposition.
I would remind you that police and emergency personnel have stood by and watched people drown in shallow water because they did not have the training certification for water rescue - and this in four feet of water.
I would also remind you that the same police have no problem arresting someone who is providing emergency aid that is considered beyond the helper's training level.
Requiring a person subject to arrest for causing an accident to provide supposition as to the medical requirements of victims simply won't fly, unless the perp is a doctor or nurse.