Frank & Aaron I did a little more digging. I could not see any kind info in the Rest API representation for a post. Then I saw:

Posting capability via custom REST API endpoint has been removed due improved Micropub support

from: dshanske/indieweb-post-kinds

At the moment I’d be more than happy to post as a draft and set the kind myself. I suspect that I’d reply using the WordPress editor, like now, rather than Drummer anyway.