Office of Sport CEO Matt Miller said he was bound by occupational health and safety requirements to act on Origin's advice and close the centre.
"I have met with the CEOs of Origin Energy (Frank Calabria) and the Office of Sport (Matt Miller) and listened to their reasoning, but I still maintain that this decision was among the most risk-averse responses I have ever seen and was a significant over-reaction," Mr Piper said.
"Geoscience Australia, the country's most pre-eminent body on seismic events, says the chance of a magnitude 5.9 earthquake within a 100-kilometre radius of Myuna Bay is 'a one-in-5000-year or longer' risk.
"The risk in this case of an ash dam wall collapsing is not in an immediate threat and is very, very remote, so I don't believe it should have warranted the immediate evacuation and closure of the Sport and Recreation Centre."
Mr Piper has met twice with new NSW Sport Minister John Sidoti who has vowed to commission an independent expert review of the advice received by Origin.
"I want to make sure that the risk is 100 per cent real," he told ABC Newcastle on Friday.
"We take this situation very, very seriously. I'm about opening facilities and I want to make sure we get the right decision as quickly as possible."
Mr Piper, meanwhile, said the cost of any shifting of the Myuna Bay facility would be met by Origin.
"I've been given assurances by Origin Energy that they will completely fund the relocation and development of a new facility at a different location if it comes to that, and I've been assured by the Office of Sport that no demolition of the existing centre or its facilities will occur in the meantime," he said.
"I understand that computers and other valuable equipment have been removed, but no destruction of that facility will take place in the immediate future."
Mr Piper has launched a petition calling for the centre to be reopened, and said the community's response to the closure had been unequivocal.
"The community has been rightly outraged by this decision and that's been reflected in the thousands of signatures being added to the petition and the thousands of emails, letters, comments and messages received by my office over the past week," he said.
"I have been overwhelmed but not surprised by the response to the petition.
"Copies are now in most of the local shops and clubs, but we've received support from people in many other areas who know and love Myuna Bay as much as we do. Those people have taken petitions to places like Mudgee, Bathurst, Sydney, Tamworth and the South Coast.
"I'm pretty confident that we'll get the 10,000 signatures required to have the matter tabled and debated in the NSW Parliament and I'm planning to get that ball rolling when the Parliament resumes on May 7."
The petition is available to sign at Mr Piper's Toronto office and at dozens of locations in the city including Toronto Hotel, Rathmines Cellars, Wangi IGA, Eats on the Creek (Dora Creek), The Bay Hotel, and Morisset Square Newsagency.