Absolutely, anything that might improve our Workplace Death, Serious Accident rates is worth a go in my book.

Sounds like double jeopardy. So if your organisation relies on Govt contracts 100% then potentially out of business but if they don't then potentially no additional or minor impact for them. From my observations this already appears to be factored into tendering for Government contracts as information regarding any Company prosecutions is required to be disclosed (usually for a specified period) and generally the questions appear to be more interested in what occurred, what lessons have been learned and what changes have been made to prevent another occurrence i.e. what level of HSE maturity the Organisation displays. So not a formal ban but potential to have an impact during the tendering process on organisations that haven't stepped up, rather than a one punishment fits all approach.

I think that this would decrease the pool of tenderers that the Gov't has to use.
There are already many companies who simply find that the hassle of dealing with Government entities is simply not worth the time.

Govt tenders - well theres a crock of the proverbial. They would prefer to go off shore or support people based on race rather than support local.

Does seem the way it is currently Andrew, but that's a whole other thing.

Interesting... I think companies being convicted will just change their name on 1 April, as many companies do every other year. Then they start afresh with a new name.

Like others said, depends on your industry. We usually work indirectly on government projects through another contractor. We waste hours on tendering every year, but never had any luck getting a government project, as we don't cover all their needs.

Why not amend section 383 of the Companies Act to include offences under the HSWA and so enable regulatory agencies to apply to the court to disqualify a director for a period of time? This might stop an SME from trading and would hurt directors of large PCBUs. This is occasionally done in the UK.
Not a perfect solution but it would be another tool in the regulatory kit.
As a further thought, Gisborne District Council just got convictions of two forestry companies under the RMA. Those companies had been previously convicted of HSWA breaches. Officers/directors of recidivist PCBUs need to know they can lose their jobs