Why not? What would you have done if you had found _him_ wandering on _your_ native world; found him sleeping on a field on Earth, red tentacles, six legs, pseudopods and all?  
How would you have handled finding an alien on earth?
mnli hypothesis: How would you have handled finding an alien on earth? premise: Why not? What would you have done if you had found _him_ wandering on _your_ native world; found him sleeping on a field on Earth, red tentacles, six legs, pseudopods and all?  