Dr Murray Heasley, now an Auckland-based spokesman for the Network of Survivors of Abuse in Faith-based Institutions and their Supporters, is a former Dunedin pupil and student.
The bishops' gathering, called to discuss the sexual abuse crisis engulfing the Roman Catholic church, wrapped up earlier this week with a pledge from Pope Francis that the church would ''spare no effort'' to tackle the issue.
The outcome outraged campaigners, who criticised the Pope's failure to commit the church to ''zero tolerance'' for paedophile priests and cover-ups.
He was also accused of being defensive about the issue after describing the church's critics as ''relatives of the devil''.
Dr Heasley, contacted in Italy yesterday, told ODT Insight the outcome was a major let-down for the survivors who travelled from 21 countries to attend events coinciding with the conference.
''It displayed a tone-deafness and insensitivity to the victims of the most horrific child sex abuse that was particularly unfortunate given the reason for the summit,'' he said.
Among the survivors was Dunedin man Darryl Smith, who travelled to the Vatican hoping for an audience with Pope Francis.
He was carrying a letter of introduction from Dunedin Bishop the Most Rev Michael Dooley, who also helped pay for his trip, but Mr Smith was turned away from the gates to the Vatican by its Swiss Guard.
Mr Smith said he was also left ''downhearted'' after Cardinal John Dew, of Wellington, declined to meet him while in Rome.
Mr Smith was New Zealand's only survivor at the event, and had met two other Catholic bishops - from Ireland and Canada - while there.
But Cardinal Dew had said he was ''very busy'' and unable to do the same, despite being the official representative of the Catholic Church in New Zealand at the event, Mr Smith said.
''If two different cardinals could see me, why couldn't he see me?
''He should have made it a part of his mission to see me, because I'm the only New Zealand survivor, in survivor week, from New Zealand.''
A spokeswoman for the New Zealand Catholic Bishops Conference declined to comment on Cardinal Dew's decision this week.
Dr Heasley said the only positive to come from events in Rome was a ''clear shift'' in the narrative, towards the voices of survivors and advocates.
That included a haka performed by Dr Heasley at St Peter's Square, which drew international media attention and sought to show survivors were now ''warriors in a battle in which we will prevail''.
It also included support from the Ending Clergy Abuse Global (ECAG) group, which endorsed a resolution from Dr Heasley calling on the Vatican to instruct New Zealand's bishops to open all archives to independent scrutiny.
''New Zealand is now squarely in the global spotlight after this Rome summit,'' Dr Heasley said.