I believe the FBI realized the public was starting to turn against them and they were also going to lose in court. So rather than fight a losing battle, they cook up a story so they may gracefully withdraw from the unwinnable legal battle and at the same time, make everyone think they have a way to hack iPhones. This way, we'll never know for sure whether or not they were successful and this is just as good, very clever actually. This story will likely disappear altogether after this week passes.