Looks like you might be right. Did some checks and it seems that the NZ authorities cannot explain why Kiwisaver is not deductible. And the way they tag some countries while leaving out others seems arbitrary.
Not sure why our Singaporean friend brought in NS liability, Key and confused the issue.
Malaysians in NZ also have EPF similar to kiwisaver, no problems for them with NZ Super.
I reckon SG CPF is problematic because of the Minimum Sum scheme, the enforced lufe annuity scheme, medi-life and the monthly payouts etc which makes it different from EPF & Kiwisaver.
Those SINKIES who renouned SG citizenship and withdrew their entire lump sum CPF never have problems with getting their NZ Super.
These SINKIES even own a small HDB flat and renting it out to get undeclared overseas income evading NZ tax whilst secretly owning a house in NZ and they also benefit from those PAP election goodies paid out to HDB tenants.