Anonymonk:
  ...or perhaps a wildly misguided attempt to untaint the input?

I might buy that notion, too, except for one thing: In the code we can see, we assign input to $value: transmute it (but not into gold); and abandon it without using it.

I wholeheartedly agree with your recommendation to use CGI or its relatives, but I don't think the code we see is doing any "parsing/decoding CGI" unless useless inconvenience to a whole bunch of electrons satisfies your definition. Rather, I have to go with OP's interpretation: lines 4-8 are useless; a longwinded NoOp; don't do anything useful.
      unless the snippet shown somehow misrepresents a bigger picture.

Oops. That's what JavaFan says below, and more succinctly! ++ JavaFan.

Update: Fixed the misquote, "parsing decoding CGI"
And later, clarified para 2.