It's not really theirs to give, is it? If a researcher has a credible narrative of what she found, when she found it, some logs and other records, and any history of research at all, most people would believe her even if the owners of the researched system said "nuh uh we're perfect don't believe anyone who says otherwise!" Especially since such a system would be less likely to be fixed at the time of the presentation, so anyone interested could verify the vulns for themselves.

Of course the courts are open for business no matter what the circumstances, so a researcher might not take credit so as to not be sued.