If you are concerned about the safety of Unix::PasswdFile I would recommend one of two options.

use a your *nix specific tool usually rmuser or such

to disable accounts (assuming no /etc/shadow) just prepend an '*' to the front of thier password,

else if you have a /etc/shadow prepend '*' to the passwd in /etc/shadow

UPDATE: Just noticed that this was my 100th post

grep

grep> chown linux:users /world