In reply to Chris Aldrich.

It also appears, that (without Webmention support) the ActivityPub plugin pulled over my syndicated response via my syndicated copy to Mastodon! Huzzah!

Why wouldn't Martha's site pick up the full response via ActivityPub via my site that also supports AP? Need to look into this and file either a bug and/or feature request for this. (Perhaps it's on the roadmap, but not implemented yet?)

Doesn't look like she's using the WebFinger plugin yet: https://webfinger.net/

And isn't listed at https://the-federation.info/wordpress, so likely no use of the NodeInfo plugin either.