Innumerable times a warrant has compelled the PRODUCTION of something.
Even blood.
Order Apples to produce the cypher.
First you are dead wrong on that. A warrant cannot turn citizens into slaves to the government. Second, even if the government could order Apple to crack the phone apple could truthfully respond that they have started a brute force attack and expect to have about a 1 percent chance in unlocking the phone in the next one hundred thousand years.
You don't understand the basics of the Constitution or Encryption.
Warrants compel one to provide something one has custody or possession of. They cannot compel something one does not have, or cannot provide. Apple cannot be compelled by a warrant to provide trade secrets, codes that are not germane to the crime. Apple is simply not a party to the action. They are not complicit. Apple does not hold the key to the encryption and cannot provide what they do not have.
If, and this is a big if, the terrorist enabled "unlock with my AppleID password” then Apple may be able to assist in unlocking the device. However, it’s unlikely the terrorist did that. Most users don’t.
You seem to think this is a simple cypher. It isn’t. Most financial institutions use 128bit AES as good enough for protecting billion dollar transactions in international transmission. This is 256bit AES. There simply is no universal key to unlocking these encrypted files. They have only one key. . . and that’s created and kept by the user, not Apple.