So what’s the point of doing this then? If the responses are overwhelmingly against whatever they have planned, would they change it?
No.
You don't base what to do or not do on the responses of the miniority of a market that tunes into a stunt on a long-dormant frequency.
iHeart already knows what the format is, and it's based either on already-done market research or a business priority (clearing Bobby Bones on a full-market signal or whatever---and then there's already-done research on how to maximize their ratings and revenue potential while achieving the priority).
As Michael (Rivers Kramer) said, it's to build interest. And for the handful of people who are listening and thinking this is being driven by listener requests, when the thing drops, they'll think it was the popular choice. Which, arguably, might be better than saying "We think Sacramento needs a (format) station, and we know how to do it right!"
But let's be clear---very little is left to chance in these things. Back in 1997, when Clear Channel owned 100.3 in Los Angeles, it was going to launch a classic R&B station. They had a "name the station" thing---mail in your idea for what to call the station, and they'll draw a winner. No prize, just involvement.
The winner---"Mega 100.3".
That night, on sister KFI, Phil Hendrie talked about it.
"Hey, wow! They drew the winning name for the FM down the hall---and it's just coincidentally the most-often used station name for classic R&B stations around the country----Mega. What are the odds? Man, management took a chance. What would have happened if they stuck their hand in the drum and drew "Asshole 100"? "