Well, this appears to be yet another short blog in a forum .. I'll answer my own question ...
Can do ... with no seen/discovered ill affects.
In light of GDPR wonder why Moodle keeps such accounts (never delete) even if Admin level users can't see them in any interface of the Admin UI. Even before GDPR, since the accounts didn't appear to have any activity on the site still tied to them, and no way I can re-call for Admins to 'un-obscure' the accounts, why were they even there?
Just thinking out loud of course ... ;)
'spirit of sharing', Ken