Unless we believe that individuals and corporations are at least somewhat autonomous. If this were Apple's device then sure, I think they should be compelled to make an effort to unlock it, but it's NOT Apple's device, and it hasn't been since it left the warehouse. Apple, in this case, is just an industry expert that happens to know quite a bit about the device. If you couldn't compel MSFT to hack the phone, you shouldn't be able to compel Apple to hack the phone. If you get a warrant to open my safe you can compel me to give you the combination, you can HIRE a locksmith, but you can't compel the locksmith. Compelling the locksmith is a completely foreign legal precedent.
I think you are rather downplaying Apple's capabilities here.
Apple is the only entity who can reliably alter the firmware to remove the forensics-thwarting restrictions, due to updates requiring a chain of trust all the way up to Apple's root certificate.
The physical device may not be owned by Apple, but the firmware installed upon it certainly is, both legally (due to copyright law) and cryptographically.
I believe there is precedent for companies having to share/reveal their own encryption keys or in this case the certificate necessary to create a firmware update. The certificate is something Apple owns.
