(The pathway to learning this is sadly typical. I requested the advice in May, the day the government announced it would be introducing legislation. Ministry for the Environment gave themselves an extension for "consultation", which ensured that it would not arrive until after the law had passed, incidentally preventing it from informing anyone's submissions. They then withheld a bunch of it as "confidential", so I complained to the Ombudsman. They released some more two weeks ago, but still withheld the really interesting stuff withheld as "still under consideration", despite the fact that the law it related to was passed months beforehand. So I went back to the Ombudsman, who clearly told them that their decision-making didn't pass the laugh test, so here we are...)
The interesting document is here. Paragraphs 9 through 19 were originally redacted. As for why, its not because they were "under consideration" - again, the law had passed, so the decisions had been made - because they basicly completely undercut the case for the law. MfE thought that the number of developments wanting to use the mechanism "may be relatively small. The far bigger determinant for major projects proceeding or not is money, especially for public infrastructure". They had no estimate of whether a Ministerial rubberstamp would actually be any faster than the usual process. Instead, they thought that the existing "call-in" process could be used just as effectively. Or, judging by that comment about money, just funding stuff. They had no idea whether the law would be effective. And they had no idea whether the system would be used by private developers because they hadn't asked.
Reading this, its hard to escape the conclusion that the government panicked and surrendered to the worst demands of the "rip up the RMA" brigade in a desperate effort to be seen to be Doing Something. Despite advice saying that that was all it would be. So in the end, it might not be that harmful to our environment. The damage done to our democracy, OTOH, and to institutional protections against corruption, is far more severe.
And meanwhile, the danger this law was supposed to mitigate, a huge Covid-recession, seems not to have eventuated. Which seems to make the entire thing unnecessary. In which case, we might as well repeal it, before it actually does do some damage. Changing that "second" to a "first" - or to "six months" - should do the trick.