And what would the full legal names and date of birth for all the admins be? Asking for a colleague.

Those reports do NOT show active zero days in signal. The pieces of spyware talked about in those are capable of reading messages once already having compromised a device which isn’t insane as if you have access to read storage from a device arbitrarily, of course you can just read the messages. If you want to solve this, A: Use GrapheneOS or an iPhone on lockdown mode with data over USB disabled or B: Use Molly with local encryption.