If passed, Tucson could become Arizona's first official immigrant-friendly city.
The protesters, mid-meeting, jumped to their feet to demonstrate.
The woman shouted: "You're in direct violation of the oath you took to the United States constitution."
To which a member of the crowd replied: "You're in direct violation of being a jackass."
Several people left as the woman spoke before police eventually escorted her and her companion outside.
However, all the while, Kack, or Green Shirt Guy, continued laughing as the incident unfolded.
Explaining his actions later, Kack said: "Just how absurd it really all was.
"Who has the time in their day to come into a public space just to spread hatred and negativity? Like honestly what happened that made them so ridiculous and hateful?"
Speaking about the Sanctuary initiative, he told Mashable: "I think it's a bold statement of morality that our community needs to make, given our history with the larger sanctuary movement and the community that lives here it's something that we need to pass.
"Families deserve to be together and all people deserve the right to feel safe."
The footage of his laughter has gone viral and Kack described the online response as "absolutely surreal".
Lou Cappetta wrote: "Some heroes don't wear capes #GreenShirtGuy."
Lydia Guzman tweeted: "How does #TucsonCityCouncil deal with racists? Laugh them out. This was one of the best ones I've seen. #GreenShirtGuy just broke the internet and I'm weak! Thanks Alex for making my day."
