I think this conflicts with the usage of alsoKnownAs property in the Fediverse (things controlled by the same entity). As I pointed out in another thread, there are two possible meanings of the word “alias”, and I think we should not conflate them. If alsoKnowAs is used to describe things controlled by the same entity, aliases should be used to describe different identifiers of the same thing. The definition of xrd:Alias seems to support this:
The
<Alias>element does not identify additional resources the XRD is describing, but rather provides additional identifiers for the same resource.
acct:ben@chatty.social and did:key:z6MkekwC6R9bj9ErToB7AiZJfyCSDhaZe1UxhDbCqJrhqpS5 are not additional identifiers of the same resource. The first one points to AP actor, the second one to DID document. Therefore, alsoKnownAs would be more appropriate here.