He spoke out both sides of his mouth in that respect.
The preface says that it is entirely a work of fiction, while he also described it somewhere as something along the lines of “inspired by actual events.”
We do know that this sort of thing happens over there, so he may have seen it personally, or heard about it from someone.
Judging by his body burning skills, I don’t think he understood the realities of what happens to a human body as a result of fire.
What’s interesting is the smell that he described in one of those screenshots. I’ll be willing to bet that his neighbors would describe the smell similarly.