Inactive user as Primary Contact?
We use project-based role accounts as the Primary Contacts for projects. This way the initial bug report goes to the project-specific mailing list instead of a person that might be away etc. (This, I think, is a bit contrary to your philosophy, but it seems to suit us)
Other than modifying the code, you could make the users inactive (but then they will appear in NO drop down boxes).
Michael H. Pryor (fogcreek)
Fog Creek Home