>moral

In Pinker's case, he's talking about society and statistics in general, but I think it's generally the case that individuals grow up within and are affected by a society - the most immoral anyone can "get away" with being in one place and time is different than another.

That particular point aside, I actually got the impression that OP was talking about moral standards in general and using the sorts of things rulers did as examples to highlight the state of affairs.

My general train of thought here is that if society and/or rulers were held to higher standards over time that it would be analogous to the arguments that Pinker makes, or more generally, to the overall idea that morality develops over time. (You don't need to think specifically about Pinker for this, as it's a point that's been made elsewhere in different ways).