rc-update shouldn't stop all services depending on net if only one net-device is stoped, but others still running.
I do not see the connection here. The "rc-update" script only adds a symlink from the script to /etc/runlevels/<level>/, or remove it, and then runs /sbin/depscan.sh. You might though be referring to the /sbin/rc script which handles the runlevel changes. *** This bug has been marked as a duplicate of 2706 ***
Thats right. Bad research from me, sorry.