Actually it can't be, barring successful attack against the physical hardware, firmware, or underlying cryptography. SGX employs public-key cryptography to auth

Actually it can't be, barring successful attack against the physical hardware, firmware, or underlying cryptography. SGX employs public-key cryptography to authenticate itself to the end user remotely (the same as SSH). The key it uses is signed by the hardware vendor, so you most certainly won't be able to emulate it. That being said, I have serious misgivings about any hardware I own and use being explicitly designed _not_ to do my bidding. I can certainly see the utility of such an arrangement for a cloud provider though.