bbPress.org

Nothing with roles, actually something much simpler.

As an administrator, I would like to have a drop-down list on the post-form.php that has a list of all forum members, so that I can assign or change the author of a post.

Within the <?php if ( is_bb_tag() || is_front() ) : ?> there would be another drop down list, but rather than forum, would be the list of authors to say started that topic.