Apple changed its encryption scheme so that they no longer can unlock iPhone 6.
That is the technical issue.
They no longer have the decryption key.
The phone in question is not an IPhone 6. It is an IPhone 5.
Therefore it is not a technical issue.
They no longer have the decryption key.
They are not being asked for the decryption key. They are being asked to update the firmware to remove the number of password tries limitation, and the time delay limitation for password entry.
They are to be allowed to maintain custody of the phone until a brute force technique unlocks it.