Mr Hendrikse said he supported the Government's plan because he was "completely certain'' Gillies had no desire to be a "normal guy''.
The proposal was sparked in part due to the pending release of repeat sex offender Stewart Murray Wilson, dubbed the Beast of Blenheim, who was jailed in 1996 for offences spanning 25 years, including rape, attempted rape, indecent assault, wilfully ill-treating a child and bestiality.
The former detective who led the investigation into Wilson, Colin Mckay, also supported the move.
He told Radio NZ: "I think the Minister of Justice (Judith Collins) has made it very clear that it only relates to a very small minority of people ... and I think that the Wilson case (and) the Gillies case are perfect examples of why this legislation is very required.''
The Green Party said the proposal was unconstitutional and would breach the rights of people who have served the time for their crime.