We have our database access set to None, and we can't shutdown the
database, even from root:

Using full path:
[root@rxsaccessdb root]# gfix -shut -attach 60
/opt/firebird/db/AccessRxs_1-1-2.fdb -user sysdba -pass ********
Access to database "/opt/firebird/db/AccessRxs_1-1-2.fdb" is denied by
server administrator

Using alias:
[root@rxsaccessdb root]# gfix -shut -attach 60 accessrxs -user sysdba
-pass ********
Access to database "/root/accessrxs" is denied by server administrator