The warning makes no sense in that situation. It tells you to use a copy of Perl that's known to be safe instead of relying on $^X, while the OP's problem is that he doesn't know where his Perl is located.

The warning applies to the method used in your solution too. In fact, it applies to all answers to the OP's question other than those that match the pattern "I talked to your service provider and they told me to use the Perl located in XXX."

Furthermore, if the OP made a copy, he probably wants to use that copy (especially if he patched it).

The usual case for using $^X is to spawn a subprocess. The warning applies to launching child processes from setuid scripts (or code that might find its way into one).