Everyone saying that the MC suddenly went all edgelord, you have to remember, teh MC has not encountered a single human up to this point (If I remember right Iruna technically isn't full human?) He very well might has built in aggro against humans because of his race. But yeah he has always encountered relativly tame and friendly situations and never experienced 'hate' until now. So while yeah it's kinda shocking, that could be how he has been since he was reincarnated, and it just never came up.
I do think they should've eased into it myself, but I like the fact that the MC clearly has lost his 'humanity' and not that weak approach so many isekai take of "I'm so strong I lost my common sense" kinda thing.