Mr Peters said New Zealand's existing policy was unusual, and was not applied in Europe, the US, or Canada.
"So many areas of health care are seriously underfunded whilst we are getting huge numbers of people gaining access this way who spent adult life in some other economy," he said.
Analysis by Business and Economic Research Limited (BERL) estimated that the measure had net benefits of $100 million a year, mostly in elective health care savings.
The bill was backed by some insurers, including the Health Funds Association, and also the Police Association.
But it did not have the support of National, which described it as anti-immigrant and filled with hidden costs. Health Minister Jonathan Coleman has said an insurance rebate for over 65-year-olds would cost up to $150 million a year.
The bill has been found to breach the Bill of Rights because it unjustifiably discriminated against family status and national origin.
A report by Attorney-General Chris Finlayson said no rationale was given for exempting Pacific migrants, or limiting the measure to the parent category.
Mr Peters has previously said the bill targeted the parent category because most migrants were older than 60 and were likely to have higher health costs.
The Attorney-General's report said targeting the parent category would not necessarily capture older people because applicants could be as young as 35 years old and migrants close to retirement age could gain access to New Zealand in other categories.
Mr Peters said the human rights assessment was "nonsense" and "self-serving codswallop".
"If the measure breaches the Bill of Rights then so does existing legislation since 2008 under National covering investor migrants, temporary work visa migrants, retirement category migrants," he said.
Affordable Healthcare Amendment Bill
• Parent category migrants required to have health insurance when they arrive in NZ, and maintain it for 10 years
• Fringe benefit tax removed from health insurance to incentivise employers to include it in a salary package
• 25% health insurance rebate for over-65s, up to the value of $500 a year
FOR: New Zealand First, Labour, Maori Party
AGAINST: National, Act, Greens
*United Future has not revealed position