Filter ajax coauthor list by taxonomy term

Each of the authors on our site has a custom taxonomy attached to their user account to assign them to a classroom. When an author selects a coauthor, we’d like to limit the auto-ajax results to only display other authors within their class (the specific term of the taxonomy). I think I’m getting close with coauthors_edit_ignored_authors, but that would mean creating a large list of excluded authors instead of just including the ones we want. Is coauthors_edit_ignored_authors the right way to go? Or am I missing a better way of doing this?