Some more news that supports this, direct from Intel this time!
https://images.anandtech.com/doci/15686/inst.png
It appears in addition to 11th gen Rocket Lake S not having Intel SGX, the follow-up to Rocket Lake S - 2022's 12th gen Alder Lake S - also appears it will not have Intel SGX. We can see this in the table as Alder Lake is not marked as having the Intel SGX ENCLV ISA extension.
This means this year's Intel 10th gen Comet Lake 10900K may be the last, most powerful chip that can decrypt the 4K UHD BD DRM for the foreseeable future.