'Participate in workflow' permission doesn't get applied to all roles when granted to Authenticated User

In the permissions admin page, when a permission is granted to the Authenticated User role, all the checkboxes for other roles are automatically checked and greyed out.
This means that it looks like those roles have the 'Participate in workflow' permission.

However, Workflow doesn't take this into account, and only the Authenticated User role shows in the workflow states admin.