Okay, if we're getting serious about it, I'm not sure I agree cruelty scales up alongside intelligence. It's an interesting take, but, as you say, it's an entirely human concept which doesn't really exist outside of our own conceived morality and can't be applied to beings which aren't capable of understanding it.

Put it this way: a cat batting a mouse around isn't considering its actions cruel or even considering its actions in a wider context at all. A human doing the same would be doing both. However, by that logic, animals aren't capable of any other abstract thought such as compassion, empathy and altruism. We are. It might be the case that everything abstract scales up with intelligence which, yes, leads to concepts such as 'cruelty' but also all the other amazing shit humans are capable of.