And, yes, it's quite possible that Caster would see his actions as normal, but I doubt that she would see it as acceptable. I think a lot of her attitude towards people (especially men) is precisely because she assumes they're all like that.
She's probably see him as an obstacle to her own plans, but she wouldn't really think "What he is doing is morally unacceptable". And even if she did, she would have no moral grounds to do so.
Medea, after originally being wronged by Aphrodite with the whole Jason thing, went off to Athens, where the king was very nice to her and loved her dearly, to plot behind his back to steal the throne for her son. She then repeatedly tried to kill the then clear-cut lawful good hero Theseus, who at the time had just cleared the highway of a number of brigands and was a stranger to the King, despite Theseus having done her no wrong other than existing as the King's trueborn son, which was unknown to father and son at this point.
She may have been the first one wronged, but that doesn't excuse that she was a villain afterward and acted poorly. She can't view the takes-what-he-wants Gilgamesh as unacceptable without looking massively hypocritical.
As for Perseus, he went to go kill Medusa because he said he totally could, and someone called him out on it. Sure he was a dick, but he hardly sat down and had a chat with Medusa about it. So yeah, Rider is biased, though research would prove her assumptions somewhat correct.
And medusa was hardly ever considered a villain, she was more of a victim than anything even in the original myth. Greek myths have a way of giving the victim the short end of the stick, and then giving them an even shorter end.
Now I need to read like, half of the Odyssey for tomorrow, so I'm going to get off the internet and stop posting or it'll never get done. So sorry, I won't reply to anything until maybe tomorrow afternoon.