Yes. The target phone, an iPhone 5C, lacks a Secure Enclave.
The password retry delay, and subsequent deletion of keys, is enforced by iOS here. Apple could provide some kind of software to allow for unlimited attempts (and an interface to do so in an automated way, which the FBI is specifically asking for).
On newer phones, the Secure Enclave contains the keys, and enforces both the retry delay and the deletion of its contents. There isn't a way around this without also upgrading/flashing the SE system (and it isn't even clear if Apple can do this in a way that preserves the keys).
Ah, I see, so with newer hardware it wouldn't even be possible for Apple to enable brute forcing with a software update. But even with older hardware, presumably allowing brute forcing is still the worst they can do, right? (Assuming no prior backdoor exists.)
The password retry delay, and subsequent deletion of keys, is enforced by iOS here. Apple could provide some kind of software to allow for unlimited attempts (and an interface to do so in an automated way, which the FBI is specifically asking for).
On newer phones, the Secure Enclave contains the keys, and enforces both the retry delay and the deletion of its contents. There isn't a way around this without also upgrading/flashing the SE system (and it isn't even clear if Apple can do this in a way that preserves the keys).