The government's contribution to help buy the land and beach at Awaroa had the support of West Coast-Tasman Labour MP Damien O'Connor - but he says he had mixed views on the campaign.
The government gave $350,000 to top up crowd-funding pledges of just over $2.2 million towards the purchase of the land in the Abel Tasman National Park.
The online campaign, which had reached its target, successfully secured the property through a tender process for a final price of about $2.85m.
The government funding will come from the Nature Heritage Fund, which enables land to be bought for the conservation estate.
Conservation Minister Maggie Barry said the seven hectare property would be held in a trust until it could be gazetted as part of the national park.
Mr O'Connor said the public motivation behind the campaign was laudable, but it had opened a wider debate on land ownership and access for New Zealanders.
"I think it's appropriate the government came in at the last minute, but I have mixed views over whole campaign.
"Initially I tried to make contact to make a donation but as the campaign rolled on I had mixed views on the dilemma and precedent it has created for government responsibility across the board," he said.
The Abel Tasman National Park is in Mr O'Connor's electorate, and he has regularly visited Awaroa over many years.
He was concerned about the precedent the campaign set for the disposal of iconic land nearby and further around New Zealand, he said.
"We have to be a bit careful. I think the crowd-funding system is a very good one for very worthy projects but I'm not sure repayment of a debt to a bank is a worthy project," Mr O'Connor said.
It has been revealed that the vendors, Wellington businessman Michael Spackman and his business partner and son-in-law, Mike Garnham, and some of their companies owed BNZ about $6m.
The bank wanted to force the sale of properties over which it held mortgages so the debt could be repaid. The case of whether or not the former owners were misled by the bank was recently put to a hearing in the High Court, which has reserved its decision.
'Always' public access to beach
"A guy had to sell up to pay his bank, so the underlying driver wasn't a motivating one for me but the fact we could have lost this ground - it's a beautiful spot - was more the point," Mr O'Connor said.
He said a loss of public access to the site, which had riparian rights and which the campaign organisers built their campaign on, was never really an issue but he supported the aim of protecting the land for wider public use.
"There was always public access except at times during very high tides, so perhaps it didn't warrant the level of emotion around it, but it does set some precedents about disposal of land in that area and around New Zealand that are iconic and important to the vista and surroundings.
"I think the fact we wanted to keep public access could have perhaps been negotiated in different ways, but it's been a successful campaign."
The wider issue of foreign ownership of land in New Zealand was something the country had to consider carefully, whether that was farmland, beachfront areas or housing in metropolitan New Zealand, Mr O'Connor said.
"And I don't think we've had that discussion. I think we should move as central government to protect the values that underpin the New Zealand way of life, and that's being able to buy a house, offer opportunities on farmland for young Kiwis and provide access to the greater outdoors.
"This campaign has probably confused a number of those things and it's time to sit down and look at what are the priorities for the government, and what happens with iconic bits of land like this."