I always found that story highly implausible, somehow this alien monster - the 'human' - has evolved a defense against one of the things that binds all life together but has a fatal weakness towards something otherwise innocuous, and it has traveled through space to the one planet where its weakness can be found!
It is just a hackneyed updating of the myth of Rolnak of the three stones, only with a sharpened stick taking the place of fire.
I guess some crafters of tale care more about the money than coherence in the tale.
