Tom Humphries is beginning a two and a half year sentence for grooming and sexually abusing a teenage girl between Dec 2010 and March 2011.
The court heard he first made contact with her when she was just 14 and took her back to his apartment after two years of regular texting.
Jason Clancy was a victim of Bill Kenneally who is serving a 14-year sentence for abusing ten teenage boys in the 80s.
He says the sentence handed down to Humphries was too leniant.
The judge reduced a four year headline sentence by 18 months after considering his guilty plea, loss of reputation and livelihood, his remorse, otherwise good criminal record and the impact on his mental health.
Jason Clancy also critisized the lack of judgement shown by David Walsh and Donal Og Cusack in providing character references for Tom Humpries.