It's nothing particularly shocking. When a community has rules, bringing in something forbidden is a grave offense, and seeing what humanity had wrought on his own people, Iorveth's reaction is an unchanging neutrality.

His Scoia'tael would occasionally, in special cases and after proving themselves genuine, take in half-elves, but never had a full blooded human been permitted to walk with them. Would someone try to bring one along, well meaning or not, the both of them would be cast back to whatever village they came to them from. Perhaps Itzal would've benefited from a place like Saskia's dream for the Pontar Valley, but those places are rare in that they go against the nature of things to exist.

Regardless, he'll make no judgment on either the man's mother or the clan that had ordered the children abandoned.

"Why did she not stay with you at the Abbey? Instead of return to the clan that wanted her children dead." The abandonment seems to make little sense to him. Even if you didn't want to live in the prosecution within the cities, surely you'd have to know the children would suffer tenfold on their own for it.