As I understand, the evidence wasn't owned by prosecution, but by Apple. It's like saying "the truth is out there", which is technically true, but shouldn't count as evidence until collected.
Then why was it used for an arrest warrant? Should evidence not be examined before the warrant is issue? Or can you just claim to have video evidence of a murder to get someone you don't like arrested?
Prosecution should be held in contempt of court if they fail to keep their own evidence securely, including the platforms and locations of storage.
I think prosecutors should go to jail if they keep their evidence in a building covered in kerosene and then "whoops" the evidence has gone up in flames.