I guess it’s better for non-fiction books in that case. Similarly I would be upset if the LLM spoiled a fiction book somehow.. like figuring out which characters will die in GoT before reading it.

I also assumed this is for non-fiction books but then I checked the Github page and the first video shows Alice in Wonderland as an example. This is the reason I asked.

Yup, think it's just a poorly chosen example. Although Alice in Wonderland does relate to Mathematics, so maybe it's a better chosen example than we realize!