“Is it the lock-maker’s duty to give the government a master key?”
No. They can only ask him to unlock one specific door, described in a warrant. If there are multiple doors (say in a case where the suspect has multiple residences) the government must issue separate warrants. What don’t you understand about the warrant process? Or the 4th amendment?
>>”They can only ask him to unlock one specific door,
I addressed that in response to your “THIS ONE PHONE” statement earlier. You said that you didn’t disagree with this part:
“In the wrong hands, this software — which does not exist today — would have the potential to unlock any iPhone in someone’s physical possession.”
This is more than one door, it’s a master key.