Traditionally, the SuperCollider server registers itself with a service discovery called «rendezvous» (or «zero-conf»), so other clients will automatically see the server appearing. You can safely disable this option, in fact there are some issues with scsynth taking long time to start up under certain wireless-LAN conditions when rendezvous is enabled.
The only reason why the preference is on by default is that the switch doesn't work with older SuperCollider versions.