Honestly if I was a security vendor who found a major vulnerability in IOS this type of behavior by Apple would make me far more likely to simply release it rather than work with them to get it resolved.
Hence why Corellium often provides members of the security and jailbreak community with access to their services.
Corellium doesn’t charge a few “nice” researchers, but builds their business around the evil researchers willing to pay $1M/yr for a license. Clearly they’re exactly like McDonalds!
People keep making very confident but incorrect statements regarding prices offered by Corellium because they assume everyone gets quoted the same, see this twitter thread for another example https://twitter.com/therealdaneel/status/1193122030687797248