Processing results takes time. Sometimes months or years. They can meet up at conferences to discuss, publish their partial results, and the mathematics community can come together to understand and piece the true answer together. None of this requires crotchety old men hoarding results, trust me, those people are smart enough not to put that in AI. They made a small result that is highly likely dependent on some input they made to the AI. The AI collates everyone's work and puts the cherry(s) on top to finalize it. Of course there is work done by the AI that only requires the sum of public human knowledge as well. But you seem very angry and accusatory at researchers, like they're some secretive cabal hoarding gold, furious at the new "give everyone our gold" machine. The people that do this science literally live for sharing and speaking and disseminating this knowledge.
Have you every used AI for work on truly cutting edge at least graduate level academic research? It's nothing like writing software, i do both professionally. Every model I've had access to requires a LOT of hand holding to get it to do the right thing. No model is getting set up with a single prompt, told to go, and then solving a millennium problem (unless they've explicitly stated that, which i would still doubt). It takes a lot of guidance to get these AIs to solve any serious problem. It's not outside at least my reach to believe that openAI is taking these nudges from intelligent people and combining those with the internal, non public models to make great press releases as it tumbled towards an infinite debt wall. I don't think there's a thing they wouldn't do to save their company.