It's not illegal when the FBI does it
So here's a question. You're the FBI's main man and you step up in front of the Judge asking for a decrypt order as "sob sob, there is no other way we can get into this phone" and you're aware that other parts of the FBI are saying "yeah we can just get this third party to do it". So, are you comitting perjury? Because it sure as hell sounds a lot like it.