Everybody knows 9 guys were killed.
And the question was
Do you want to put people in prison after every accident?
This appears to be an error of judgement.
Assuming that gross negligence and recklessness were not involves, do you want to put him in prison? If you do, then, most respectfully, youre daft.
If you believe they were involved, okay. Prison is proper. But why do you believe they were involved?
I don't know, it is all speculation.
Let the punishment fit the crime. If he isn't directly responsible, he retires.