I would have to concede the point your coworker brought up. Why would anyone want to limit themself by writing a utility script in Perl? He's right, it doesn't run on every platform: support on C64s is shaky at best, and I can't remember seeing a single port to the VIC-20. For true cross-platform compatibility it is much better to use Unix shell scripting.
Next time, educate yourself before blindly insisting that Perl is the right tool for the job.
Update: Jeez, I really didn't think I had to resort to <humour></humour> tags...