The value of the vote trumps professional opinion.
(though the staffers who live in Hamilton vote too... but I doubt that factors into the equation)
This is hardly unique to Hamilton's city council, but many of them paint themselves into corners on issues and stubbornly refuse to change those opinions, even in the face of logical, reasoned, compelling evidence. I get that they're probably concerned with being painted as a flip-flopper (which happens anyway), but they will never please all their constituents and may gain kudos from some to balance the jeers from others. And a truthful and clear explanation for the change of stance will be respected by many, even if they still disagree with the position.