The attestation report is signed by a key in the PSP hardware, not accessible by any OS or software, which can then be validated with the vendor's certificate/public-key. If that can be faked, are you saying that those private keys are compromised?
As I understand it, the big idea behind Confidential Computing is that huge American tech multinationals AWS, GCP and Azure can't be trusted.
It is hardly surprising, therefore, that the trustworthiness of huge American tech multinationals Intel and AMD should also be in doubt.