Could be people trying to find/create inconsistencies so they can claim the event didn't actually happen. Some folks see false-flag operations in anything.
People worried about that kind of thing have a lot of totally legitimate concerns regarding fire safety standards to bring up. The fact that Japan generally doesn't have fire escapes, for one thing, and the fact that the roof door, which could have saved lives, was locked. The huge focus on wood, structural elements of which could have been impregnated with flame retardant relatively cheaply at the time of construction (but wasn't) also crops up.
Although from what I've seen, conspiracy theorists are mostly fixating on the fact that the main doors were open because the NHK were planning to come over, which isn't supposed to be SOP for a press visit anywhere, and now the NHK has a big story which naturally they were first on the scene for. But that's consistent with KyoAni being in a nice area and having no real fear of anything like this happening and just generally being careless.
People just aren't comfortable with the idea that one lunatic acting alone can wreak this kind of havoc. But even if I don't think it was the main fault in this case, hopefully this is a wake up call for fire safety standards in Japan in general, since it has long been notorious among developed nations for having poor building codes.