That's what Don was talking about editing /etc/inittab for; before you kill aolserver, comment out the nsd respawn line and run "telinit q" to get init to stop respawning nsd. Then reverse your changes when you have finished kicking postgres. (So you will need two "telinit q"s in there.)
When you are shutting down I don't think it will be an issue, because hopefully you don't have nsd set to respawn in runlevel 0. :)
