DL is edging closer to the requirements which DOT permits, but is still not there yet. I doubt that DL (or UA) is particularly worried about a legal challenge to something which DOT specifically authorizes.
The major item missing from DL's new requirements is that the passenger provide medical documentation of treatment for a DSM-recognized condition. That means having a licensed professional conduct a diagnonstic assessment and written records of a recognized condition. Not that many people want those sort of records out there when they are not true.