Maybe the engineer thought the emissaries were all robots? His worst fears had come true - the human race had already become the threat they had foreseen. It appears he had to touch David's hair to find out what he was, so there is no reason to assume he would know the true nature of the rest of the envoy.
Nonentity had some good ideas regarding an AI god [1]. However I think there is strong evidence to suggest successive AI creations in this universe; the successive overthrow of the creator by its intellectually (even emotionally) superior AI creation [2]. The xenomorph was bound by the Engineers after a great war, the human race is not keen to be ruled, and neither is David - "doesn't everyone want their parents dead?" Perhaps a new creation has about as much natural concern for its unnatural parents as that of a competing species (hence the carnivore). What would humankind do if they had deployed an AI civilisation that was getting out of control and was on the verge of creating its own superior race?
Nonentity had some good ideas regarding an AI god [1]. However I think there is strong evidence to suggest successive AI creations in this universe; the successive overthrow of the creator by its intellectually (even emotionally) superior AI creation [2]. The xenomorph was bound by the Engineers after a great war, the human race is not keen to be ruled, and neither is David - "doesn't everyone want their parents dead?" Perhaps a new creation has about as much natural concern for its unnatural parents as that of a competing species (hence the carnivore). What would humankind do if they had deployed an AI civilisation that was getting out of control and was on the verge of creating its own superior race?