Trevor Easton, general manager of lesbian, gay, bisexual, transgender and intersex (LGBTI) support and counselling service OutLineNZ, said Mr Williamson's comments would have shocked people "20 years ago, never mind today".
"I think it's absolutely appalling that someone from Parliament in this day and age can come out with sexist comments and homophobic comments," he said. "It's immoral, it's unethical. It's just shocking, absolutely shocking."
The gay community would feel "betrayed" by Mr Williamson, he said, believing him to be a supporter of LGBTI rights following his 2013 "big gay rainbow" speech in Parliament in support of legalising same-sex marriage.
Carmel Murphy, who founded Women in Business, said there was a "level of responsibility and conduct" that came with Mr Williamson's role. She said she felt as though his behaviour was "counterintuitive" when it came to encouraging women in the workforce and making them feel welcome in senior and executive positions that have typically been taken by men.
The criticism comes as a National Party source yesterday revealed Mr Williamson was set to announce his intentions for the Auckland mayoralty shortly.
Mr Williamson was due to speak on local transport issues at a public meeting in Pakuranga next Monday. Howick councillor Dick Quax said he could use the event to announce he is going to run for mayor.
Prime Minister John Key said in Christchurch yesterday that Mr Williamson's speech was "probably not the threshold for leaving Parliament".
"I suspect he's had a chance to reflect on it and probably acknowledges that he has over-stepped the mark. Everybody knows that Maurice is a bit flamboyant, a bit sort of out there sometimes. My understanding is that he wasn't there in his capacity as an MP. That doesn't absolve him of the things he may have said or done."
Additional reporting: Nikki Papatsoumas and Kurt Bayer.
