We could choose to be benevolent to octupi in a number of ways. We know killing them is bad from their perspective. We know that some like making homes and all like eating certain eating food and we know many other things. We could get very far by acting in accordance with their apparent desires and simply not exploiting them or their environment.
You can only even perceive their apparent desires to the extent you can map them onto your own experiences.
You could offer them language for controlling you, and they could learn to use it according to their desires, through trial and error, but without shared bodily experience you cant understand those desires.
And them being able to control you doesn't solve the benevolence problem. Because benevolence is understanding without ceding control. For you to be benevolent you need to actually understand them, which requires shared experience.
This is why I think consent is a much better basis for social coordination than benevolence.
In the case of AIs it is somewhat moot, because the first general/hard AIs will be clones of humans in humanoid bodies.
Luckily we live in bodies that are almost exactly the same as dogs.
The reason why you empathize with a dog more than an octopus is precisely because our bodies are similar.
Do you have another theory as to why we empathize with dogs more than, say, a forest, or a hive of ants?