>  CONFIRM listname FOR user@node
 
Remember that when a user is in the magic-cookie mode
of subscription that in fact they are NOT yet subscribed
and don't show up in the subscriber list.  Thus the
would-be subscriber does not yet have a list-owner.
 
Yes, 3rd-party CONFIRM can be done by the owner, but that
isn't magic-cookie.  Heck, the owner can waive (NORENEW)
the subscriber.