Additional info:
Regarding handling expired guest accounts: On conferring with my colleagues, apparently v6.0.66 also did not delete the guest users, but since the guests.db database was a text based file, we were able to get around that with a cron job that deleted the entries. But since the database is now a redis database, that script no longer works.
It appears that on the enterprise terminal server instances that running /usr/NX/bin/nxserver --userlist --guest
will trigger deleting expired guest users, but since that command is not working on the terminal server nodes, nothing appears to trigger the deletion of expired guest users.