Prime Minister Jacinda Ardern has conceded her language was "a bit blunt" when she called an MIQ guard a liar, but maintains he and his employer bear some responsibility for the latest testing failure.
The worker's employer First Security, meanwhile, has placed the blame on the Ministry of Health's testing register system.
Authorities yesterday confirmed the Grand Millennium guard - known as Case B - went five months without being tested for the virus despite a requirement to be tested every fortnight.
Ardern later told Parliament and reporters that the man had lied about being tested.
Asked whether she stood by her comments a day later, Ardern said the government expected border workers to undergo regular testing and their employers to police that.
"I was probably a bit blunt, but it doesn't change my view of the roles we all have to play."
Under questioning, Ardern acknowledged the government was the "final check and balance" and so also carried some of the blame.
"We do need to check we are doing our bit in ensuring people are being tested," she said. "We do know that we need to improve that system.
"We are a final backstop though: there is a role for an employee, a role for an employer, and then there's us."
Since the mishap, Covid-19 Response Minister Chris Hipkins has signed a public health order that will make it mandatory from 27 April for all MIQ employers to use the Ministry's national testing register.
In a statement to RNZ, First Security said the firm already provided all its workers' personal information to the register.
It said that system did not flag the guard as non-compliant until 26 March "at which time the follow-up process began".