The cruelty inherent in Elpis is not just in the unmaking of creations - but in their creation too. These beings are designed the way they are by the ancients - and then put in an environment to be studied and observed for their suitability or continued existence. But they have no capacity to understand or comprehend that they are being studied, that their innate nature might lead to their destruction through a series of criteria that they have zero control over or knowledge. Creating life, only to destroy it if it doesn't live up to the standards of the ancients, this is the cruelty that Hermes sees. And with it, you can kind of see his reasoning for wanting to subject mankind to a similar test that they have no capacity to understand or comprehend. "Why does mankind deserve to live any more than our creations? Who is testing our suitability for survival?"

And frankly, does it really matter if the Lykaon's have souls? Was the Lykaon not fighting for its survival before it was killed, was it not suffering as it died? Is it not tragic that creature that was simply following the nature given to it had to die, through no fault of its own? Why does our empathy for life suddenly come to a halt if that life doesn't have a "soul"?