Seems WorkSafe has got the guts (and the law, and the evidence, presumably) to do something.
A prosecution means that justice is seen to be done. More importantly, it reinforces that no-one is below the protection of the law; no-one is above its scrutiny. The protection of law is common to all, not just to the upright and the virtuous. And so it should be!
Whatever your thoughts on Mr Ward, the fact is that a man died. It is entirely appropriate that WorkSafe investigate whether that death was due to unsafe work practises, and prosecute if it sees fit.
I am aware that Mr Ward is no saint. But consider this: what if it had been your father in the van? Your brother? Your son? Even if they had a criminal record, even if they were being hauled off to face a drink-driving charge, wouldn't you want their death fully investigated? Wouldn't you want those responsible to face some sort of justice?