I hear this kind of reasoning often, but I don't believe anyone is willing to apply it outside of food.

Yes, many non-human animals would eat you if given the opportunity. Some species of large cats might also kill you for amusement. Does that fact justify you doing the same? Many animals might try to copulate with you. Does that justify bestiality?

And if you're comfortable with moral arguments based on reciprocity, where does that leave humans such as babies? They certainly cannot extend any moral consideration to you, but I assume you're willing to overlook that?