Shamima Ali, of the Fiji Women's Crisis Centre, said the fact that Nasilasila's non-parole period was six years also highlighted the complete disregard by the department to allow him to participate in training with the Prisons and Namosi rugby teams.
"Barely eight months into his sentence, he can go and play club rugby publicly, and he's glorified by the prisons services and so on," she said.
"Rape is a terrible crime in this country and we have high rates of rape, and they are very hidden. There's a huge conspiracy of silence around rape in Fiji and we believe up to only 5 per cent of cases are reported."
Surveys shows the scale of domestic and sexual violence
According to a survey carried out by the crisis centre in 2011, 64 per cent of women have experienced domestic violence - emotional, physical and sexual.
Sixteen per cent of women surveyed also said their first sexual experience was before the age of 15 and it was forced.
"One in three women get raped in Fiji and up to 5 per cent are ever reported," Ali said.
"The youngest child that was raped was 4 months old with the oldest 90 years old and everyone in between including people with disabilities."
She said no one was exempt.
"For us, the message being sent out here by the Corrections service is that it's okay to commit such a crime with impunity, go to jail and yet you can get away with - you can go about your daily business.
"This also sends out the wrong message to victims, survivors and other women - one of discouragement from reporting and increasing the trauma of the survivors."
Ali said the situation reeked of disregard and disrespect to women, girls and children and seemed to show "that it doesn't matter, that this heinous crime committed against women is of little consequence".
The Corrections Services said Nasilasila's not the first prisoner to be allowed to participate in public sports nor will he be the last.
The Director of Rehabilitation, Senior Superintendent Salote Panapasa, said Nasilasila had his day in court and was now under the care of the department.
Panapasa said the department knew what was best for Nasilasila, as it had professional psychologists and counsellors that had assessed him and ensured that he completed the necessary rehabilitation treatment programmes to be eligible for such activities.
She said recent comments in the media and online over the participation of prisoners in sports, especially against Nasilasila training with the provincial side Namosi for the Skipper Cup competition was "disheartening and counterproductive to all the good work in the rehabilitation efforts" at the department.
"We do not condone the actions of Nasilasila, however, it's our duty at FCS to positively address his offending behaviour," she said. "Nasilasila has displayed the necessary progress expected of him since his incarceration.
"We implore the public to understand that one day all those in our Corrections centres will eventually return to society. They all deserve a second chance."
But NGOs FEMLinkPacific and Fiji Women's Rights Movement said they were deeply disturbed and disappointed by Panapasa's comments.
The groups said Corrections had displayed double standards for sportspeople convicted of rape and called for an investigation into the government department and its remand and rehabilitation processes.
Movement director Nalini Singh said she was appalled that rapists and sexual offenders were considered "low risk" by the Corrections service.
Singh said this was an insult to the victims and survivors and everyone who had been pushing to end violence against women.
"There have been efforts at national level by the government and across all sectors of society to eliminate sexual violence and yet the body tasked with the rehabilitation of criminals is reinforcing the rape culture," she said.
FEMLink's Susan Grey said no one was above the law and the double standards by the prisons department was unacceptable and must be called out.
Grey said they were also concerned at the conflict of interest at play here - that Commissioner of Corrections Francis Kean was also head of the Namosi rugby club which Nasilasila had been training with.
This week, the Fiji Rugby Union announced Kean was stepping down as chair of the FRU after a controversial five-year term.
In 2007, the former navy commander was sentenced to 18 months for manslaughter after pleading guilty, but he only served a week behind bars.
In 2016, Kean was appointed to head the FRU by Prime Minister Frank Bainimarama, who is also Kean's brother-in-law and President of the FRU.
In April, Kean stood down from the World Rugby Council and withdrew his nomination for a seat on its executive committee following allegations of homophobia published in the Sunday Times in Ireland and a damning open letter to voting members by former Samoan rugby international Dan Leo.
FEMLink questioned Kean's influence in Nasilasila being allowed to leave the prison complex and participate in public sports.
"In a country where rape and sexual violence statistics have hit crisis level, what kind of message is FCS sending to the public?" Grey said.
"There's a lack of assurance that perpetrators of sexual violence are being held accountable.
"The FCS' comments undermine its pivotal role in women's access to justice and threaten the progress of attitudinal change towards gender equality and ending rape culture."
The women's rights groups on Wednesday launched a petition calling for an independent investigation into the prisons' rehabilitation policies and want the government department to "reform towards a human rights-based approach that ensures equal treatment for all".