User with multiple roles

Currently, Edit Author Slug picks the first listed role, which is standard WP behavior, and should normally result in a default WP role. This will likely change in the near-ish future, now that WP 4.4 will be exposing all roles in the user list under wp-admin.

I forgot to mention earlier that there is a a filter in the code that will allow you to pick something other than the first listed role. Take a look at the ba_eas_get_user_role filter/function if you’d like to change the default behavior.