You are way overthinking this. Witnesses reported blue light, so hollywood did blue light. It's a movie not a documentary. Regardless we know from the witness

You are way overthinking this. Witnesses reported blue light, so hollywood did blue light. It's a movie not a documentary. Regardless we know from the witnesses in the room the criticality at least lasted long enough for Louis to need to use his hand to separate the cores, which is clearly not nanosecond scale, so I'm not sure what exactly you're expecting or criticizing here. The only difference I can find googling is that he apparently used one hand one screwdriver, not two.