Uhm, we may have gotten wires crossed somehow. Streams supports  Mastodon's Move activity and moves a fediverse account in accordance with the procedurre used by Mastodon.  This has nothing to do with Streams nomadic identity mechanisms.

Nomadic identity does not use the Move mechanism, because a copy was already made and there is nothing to move. Streams does report nomadic instances in alsoKnownAs and provides information that a nomadic clone was created (as opposed to a one-time migration) via the copiedTo property. Sites and projects which wish to support nomadic identity may make use of these properties to discover and link the different identifiers.