simply because I had never used the Resurrect-O-Nomitron.
Any Sim you've resurrected with Resurrect-O-Nomitron will become a member of the household. Making him unselectable will not turn him into a dormie. Like jsalemi said, use Inge's Teleporter.
syberspunk has a
hack that lets you choose whether to add the resurrected Sim to your household or not. It's last updated to Seasons though, so it may not work in the later EPs.