WhiteNoise is mentioned in the post.
It seems the AS is a mapping from some other identity to a pubkey. This is a worry if there is an "other" identity. nostr:nprofile1qqsvnx99ww0sfall7gpv2jtz4ftc9v6wevgdd7g4hh7awkpfvwlezugpz4mhxue69uhkummnw3ezummcw3ezuer9wchsx06t26 just like nostr already has pubkey identities, so what's the problem.
Discussion
What's not mentioned is how nostr:nprofile1qqsvnx99ww0sfall7gpv2jtz4ftc9v6wevgdd7g4hh7awkpfvwlezugpz4mhxue69uhkummnw3ezummcw3ezuer9wchsx06t26 is different from Whitenoise. Both use pubkeys as identities so both can use MLS without AS.