I understand the point, but you're missing the issue. DJs get calls from people from all walks of life. Some are the genuine article, some aren't - they don't know whom to believe and cannot be held liable for the content of the information.
I can rell you that I'm a climatologist and that all the fossil fuels that are being burned to keep your computer on the Internet are contributing to Global Warming, but it doesn't make any of it true. You can choose to believe that GW is caused by substances such as fossil fuels, or greenhouse gases, or cows farting in New Zealand. The fact is that, depending on your beliefs, it doesn't make any of it true. A court might allow one of the attorneys to introduce this as "evidence", but it doesn't make any of it binding on either the DJs or the station.
However, had there been a nurse in the studio during the contest, the whole story would be substantially different. But, as far as we know, that was not the case.
By the way, I'm the Surgeon-General of the United States. Don't smoke and practice safe sex and . . . . . stuff like that.
Their response to a warning that what they're doing will, or could result in death does count. What matters is the rational content of the warning. It doesn't matter if the caller was a construction worker.
Regarding something like global warming, it doesn't matter how they respond, because there's no direct risk of injury, or death.
Re: GW
"The fact is that, depending on your beliefs, it doesn't make any of it true."
The mechanism is real. Otherwise, it's the magnitude of the effect that's important. The magnitude of the effect is small an inconsequential. What anyone in particular believes is irrelevant, regardless of credentials. It's the facts that matter.