Why do you ask this question? You know he doesn't. But that doesn't mean it is false.

If his username is anything to go by, I'd say that there is probably a kernel of truth to his statement. After all, people don't just make up stories about ketamine and nitrous addictions.

Especially since dying in a house fire isn't a usual route to go. It might make sense he was on ketamine and somehow a fire started (he probably didn't intentionally start a fire), and couldn't get out. It's very hard to walk straight on ketamine. You end up walking like a robot.

Edit: but the real reason I believe these claims is because my gut says it is true. Not the best reason, of course. But not a bad reason either.