By the time a patch is publicly released like this, I'm sure Apple will have it decompiled and know what the exploit is within weeks if not days since the actual exploit code won't be much code to analyze (as opposed to digging through all of iOS like the jailbreakers have to do find an exploitable location).
Plus, Apple I'm sure has plenty of software/hardware debuggers they can attach to their own hardware that'd let them know what is happening even if they didn't have the closed/open binary.
(Days matter.) Another issue is that open-sourcing the exploit makes it easier to use for nefarious purposes in the mean time, and it isn't like knowing exactly how the exploit works actually helps end users protect themselves, due to Apple's platform policies. In essence, this is all a really dangerous ethical tightrope to be walked.