The Intel response seemed odd. They say you need to only run software from trusted sources. But if we only run trusted software the need for the enclave goes away. The only use then is for running code on a machine you dont trust. In the cloud.
The largest consumer application of this is DRM - modern UHD Blu-Ray playback on a PC requires a fully SGX-enabled backend; the negotiation to obtain playback keys and the decryption of the on-disc content is done in the SGX enclave.
We've already seen the Sony rootkit fiasco, so it doesn't seem unfair to say one should not trust what DRM providers are doing. We should definitely not let their malicious garbage run in a secure onclave where you can't tell what it's doing as suggested by these researchers.
In the cloud situation, the customer doesn't trust the cloud provider beyond just running his/her software (but inherently trusts him/herself). The cloud provider doesn't trust the customer to respect its isolation boundaries and must defend itself from SGX enclaves (and indeed all other client software) appropriately.