I think a little background is in order. Nik came onto EFnet #Perlhelp as Apost asking for help with his code. Originally all he had was an open call that took a filename from user input, i.e. open(FILE, "<../some/dir/$user_input"). He was told that was a security hole, but he didn't believe it was. He was then shown it was a security hole when someone gave him a URL that caused the script to read /etc/passwd.
As the discussion went on someone mentioned any arbitrary program could be run. This, of course, was false, and the person was corrected. However, Apost became curious, and asked how his code could possibly run an external program. He was told that if he removed the leading "<" in his open call then anyone could supply a command if they did it just right.
Yes, he explicitly changed his code to allow for an even bigger security hole, after he was told it was a security hole and what it would allow.
The full log of the conversation can be found here.