Get the terminology right. Runlevel 0 is known as single user mode and it is not in anyway halted. The idea is that init, a shell and not a lot else runs. So that's fair enough. But why did you (in the general sense) install Redhat and not disable all those insecure daemons you didn't need running in the first place ?
I'll just mention that this might be a bad state to leave a *BSD system in because it knocks down the intended securelevel. securelevel locks raw device access, immutable files and so on.
Jon