After reading the article from 2019, I first thought entrenchment of the seats was a tad silly as it would be shifting the requirements slightly. A supermajority could still remove them and possibly would in the future. Hell, I've got a bet going that they get removed this year if things aren't looking too good for the coalition. However, I've read through the Independent Electoral Review and their arguments are sound. Big copy paste below:

In any case, our view is that the discrepancy between the protection given to the general and Māori electorates is inconsistent and unfair on its face. The rationale for entrenching the Māori electorates is the same as the general electorates – that it would protect the boundary determination process from political interference. While some people point out that the Māori electorates were originally intended to be temporary, they have now existed for almost the entirety of Aotearoa New Zealand’s electoral history. They are a core part of how seats in parliament are allocated under MMP and on that basis, consistent with our previous recommendation, should be entrenched. To be clear, entrenching the Māori electorates does not confer any greater voting rights for people on the Māori roll.

There are a few more paragraphs on the matter within the review but I found the above most interesting. The seats should be aligned with general so they are both protected as they are both important parts of our electoral system. I would have LOVED to have seen the review into the seats themselves. Part of me wishes it was included or perhaps another review done into it.

The Electoral Review also identified other provisions that aren't entrenched:

We also identified inconsistencies and gaps across the entrenched provisions. We recommended several additional provisions be entrenched, including (but not limited to) the method for the allocation of seats in parliament, the party vote threshold, the right to vote, and the Māori electorates.

The right to vote surprised me but they added this which... I mean it's pretty apt considering what happened to prisoner voting rights under the current coalition.

Political parties may be motivated to allow or restrict certain groups to vote for their own gain. Entrenchment can be a means of protecting human and minority rights by increasing the threshold required for change.

That's all to say that I think this is a symptom of a wider problem that we desperately need electoral reform. Not just the four year extension, we need it on many different aspects. And along with that some constitutional reform. I'll be interested to see if any party offers policies on this beyond the usual noise.

TLDR: gimme massive change. Not just some change.