From the Article:
Versions 7.5 and 7.6
select se.OwnerGuid
from SecurityEntity se
left join Item i on i.Guid = se.OwnerGuid
where i.Guid is null
version 8.0 and later
select se.OwnerGuid
from SecurityEntity se
left join Item i on i.Guid = se.OwnerGuid
where i.Guid is null and OwnerGuid <> '0FFFFFFF-FFFF-FFFF-FFFF-FFFFFFFFFFFF'
If you test the SELECT first so you know it's bringing back the correct Items you wish to update,
You should just be able to change the WHERE clause.
OwnerGuid <> '0FFFFFFF-FFFF-FFFF-FFFF-FFFFFFFFFFFF'