I feel like this is all smoke and mirrors to redirect from the likelihood intentional silicon backdoors that are effectively undetectable. Without open silicon, there's no way to detect that -- say -- when registers r0-rN are set to values [A, ..., N] and a jump to address 0xCONSTANT occurs, additional access is granted to a monitor process. Of course, this limits the potential attackers to 1) exactly one government…
The technologies Apple PCC is using has real benefits and is most certainly not "all smoke and mirrors". Reproducible builds, remote attestation and transparency logging are individually useful, and the combination of them even more so.
As for the likelihood of Apple launching Apple PCC to redirect attention from backdoors in their silicon, that seems extremely unlikely. We can debate how unlikely, but there are many far more likely explanations. One is that Apple PCC is simply good business. It'll likely reduce security costs for Apple, and strengthen the perception that Apple respects users' privacy.
> when registers r0-rN are set to values [A, ..., N] and a jump to address 0xCONSTANT occurs
I would recommend something more deniable, or at the very least something that can't easily be replayed. Put a challenge-response in there, or attack the TRNG. It is trivial to make a stream of bytes appear random while actually being deterministic. Such an attack would be more deniable, while also allowing a passive network attacker to read all user data. No need to get code execution on the machines.