Correct me if I'm wrong, but didn't AMD already do this? The TPM functionality is implemented by the PSP, which makes largely the same claims as Pluton here.
Or was AMD lying somewhere about PSP capabilities?
Oh, and the PSP has already been hacked. Along with the IME. Seems the super secure secret environments running God-knows-what signed proprietary firmware weren't so secure after all! How is Pluton (supposedly) different?