As described in the article, PTT includes a TPM running on the ME. The CPU loads the ME firmware (which is validated against a key on the ME), then starts executing the rest of the firmware (including copying measurements to the TPM).
So it just boils down to TPM-protected encrypted storage? That obviously works (because it's how a bunch of devices work today), but it's a lot less exciting... if you can set up a full TPM stack for sealed storage (which we don't have on consumer linux today :( ) then I don't see what attacks this "stateless laptop" defends you against that the TPM doesn't already handle.
