Well they're selfish enough to either not care, or think that "they got beaten because they're weak, we're different 🗿".
And why would anyone in that world believe the word of Humans?
Nah, he's bummed that his normal life is ruined, how people expect him to be grieving, how they look at him with pity.
This chapter proves it, it was never about Taiga's death, but Taiga dying.