Theory about the creeper

I am sure this has been explored before so bear with me. The "Creeper" is actually a galactic bounty hunter much like the Predator tasked with finding and destroying a parasitic threat on Earth. The ones that it chooses are the ones that are suspected of being infected. Usually they are unaware they have become a host. Creeps 'smells' to see if he and I use he loosely here can detect the parasite. This could explain why some of the 'victims' are stitched up. Creeps also consumes the body parts that have been damaged so he can regenerate. There is only a short window where the parasite is most active and that is why the creeper is only active during certain times. The theory of course could be way off base with little evidence backing it up. Only the screenwriter and director really know for sure.