As of last month Google added support for DiscussionForumPosting schema (which Discourse already does well) and ProfilePage schema:
They currently recommend linking discussion posts to an author.url page which is:
A link to a web page that uniquely identifies the author of the post, most likely a profile page of the forum. We recommend marking up that page using profile page structured data.
As far as I can tell, having indexed ProfilePages linked to discussion posts is the only way for forums to rank in Google’s new Perspectives search. All of this is incompatible with noindex’d profile pages.
Given this latest news, would you reconsider indexing profile pages and adding the schema from the OP?