Received from J_Catlady at 7/29/2018 07:38 PM UTC:
p.s. Of course I later went into the site to find out who it was. But I think that either the alias info should be available to moderators in general, and/or the member info should be available in the emailed pending-message notice.
This seems like a matter that should be handled between you and the group Owner. I don't believe it's appropriate for Groups.io to make changes that bypass the privileges the group Owner has chosen to not give you as a Moderator.