Here is the description of that option
•Use a LiveUpdate server
Downloads content updates from either the default Symantec LiveUpdate server over the Internet, or from an internal LiveUpdate Server. You can specify multiple internal LiveUpdate servers for failover support.
I don't want it to use an internal Live Update server, ever. I'm going to try putting a "fake" server in the "Use a specified internal LiveUpdate server". Hopefully it will try to connect up to the fake one, fail, and connect up to the internet.