Well, it doesn't actually assume that - it raises the issue, and provides a basis for discussing it.

When it comes to other animals, I personally tend to give them the benefit of the doubt, though I don't think there is much room for doubt, in the case of snails, as to whether they have inner lives (for example, I think cone snails are dangerous, but not evil.)

AI is an interesting case because the discussion of AI ethics is almost always about having AI behave ethically towards us.