Frankly the FBI should have just requested the bootloader signing keys, bootloader documentation and just write it themselves. The only protection then is the 5A - and apple can't take it because it is them on the stand.
My belief is that the Feds already had the tools they needed to get the information they needed off the phone, but wanted to use the situation to create a new standard of practice as it was too juicy to pass up—never let a horrific event go to waste.
Luckily, it didn’t work in the way they hoped or at least to my knowledge, it didn’t.
