[Gus's own brows arch up in surprise. What kind of a question is that!?]

Uh, yeah? Everything has feelings! Even the kind of demons without faces have feelings!

[...He's pretty sure, at least. He hasn't met all the faceless kind of demons on the Boiling Isles, but he can be aghast on their behalf.]

And even if they didn't, it's not right to come into their home and kill them just because you don't understand them!

[Yeah, maybe a nerve has been touched a little bit. Or a large bit. His tone makes it clear he's speaking from some personal experience.]