It is an essential service so has operated through all levels of lockdowns — robyn moses

My understanding is essential services (supermarkets, pharmacies, gas statios, etc.) are not allowed to implement the Vaccine Certificate scheme (at least that is the message for now).
Also all the current Government information (e.g. the covid19.govt.nz website is regarding Vaccine Certificates for public to enter a venue/event/retail/etc. location, so if your company isn't open to the public then I wouldn't expect it to be reasonable to use Vaccine Certificates to control entry... but I am learning to not expect the rules to be logical.

So effectively this is the CEOs of most of NZ's large companies saying that there is no need to do a risk assessment anymore before we mandate vaccinations in any of our organisations — MattD2

I disagree with this Matt.

Top of page 2: Item 2 under The approach states "Specific risk-based assessment"
First bullet point on page 3 begins "Undertake a risk assessment, which may capture specific roles, groups of similar roles or your workplace as a whole."

The final sentence on page 2 is: "The Forum’s leadership position is that vaccinations are the most complete and robust control we have today.".
And second last para page 1 begins "This is a leadership position, not a legal opinion."

I find the statement very clear with excellent reasonings and methodology.

It is an essential service so has operated through all levels of lockdowns

Thank MattD2, yes I am aware of all you have said, I doubt if my PCBU and HR are aware, I have had to correct so many of their assumptions a number of time through the course of implementing the business plan on the floor, each work site has a HS Advisor who all have been sidelined from the plan so I too am learning to not expect the rules to be logical

yes the rest of the document provides advice about doing a risk assessment, etc. but it leads with that statement - everything after it is pinned to that opinion that vaccinations "can be mandated for any workers' roles".
Also keep in mind that this is the forums advice to CEOs, who stereotypically do not have time to read whole reports and who rely on executive summaries to obtain key information. So it wouldn't be unexpected for them to only briefly read the first page where this is the main point (@robyn moses example is potentially a result of business leaders relying on these types of high level summaries to make decisions).

I feel your frustration!
As you said in you previous post, I also feel like "H&S" is being used as the reasoning for taking actions which are actually in place to manage business continuity risks due to Covid.
Even the PMs explanation yesterday of why vaccinations would be required for all workers where Vaccine Certificates are being used was essentially "we think people would expect that if they had to be vaccinated the workers would have to be too" rather than any sort of actual assessment of the risk.

Here's how Auckland Airport has tackled it's mandatory vaccination on our worksite policy Stuff reports on Worksafe's latest advice here

Meanwhile, Covid's tentacles have spread down and into Christchurch, my son is getting married today in ChCh, we had to make the call not to take my 91 year old mother to the ceremony or reception, as we didn't want to be the family that took Covid into her rest home.