Games : What is the point of the Anti-Gadoid gun in Dying Light?

I found the Anti-Gadoid gun (http://dyinglight.wikia.com/wiki/Anti-Gadoid_Gun) but can't figure out what to do with it:

I have seen on the web (link above):

The Anti-Gadoid Gun is a troll by the developers

Is that right? It doesn't do anything? You can use it on a side quest or something?