"The Luminaries" author sparked uproar last week at a literary festival in India when she said she was angry with New Zealand's treatment of the arts.
Her claim that New Zealand was dominated by "neo-liberal, profit-obsessed, very shallow, very money-hungry politicians who do not care about culture" provoked debate across the country.
Today, Key said the 2013 Man Booker Prize winner's political views carried no more credence than those of McCaw or prominent businessman Peter Leitch, who started a chain of butcheries and trades under the name of "The Mad Butcher".
"Obviously it's done phenomenally well and I'm really proud of her, but it would be no different from Richie McCaw or the Mad Butcher or anybody else having a view on politics.