His head just did that, but milliseconds later his head, which was in the process of exploding, got hit by like eight different bullets and the psychic brain exploder ray!
I think the JFK assassination was a completely normal assassination and they caught the killer immediately, but then a time traveler went back and fucked with it and made it ambiguous, and then another time traveler went back and messed with it even more, and now it's just a time traveler meme to go back and make that specific event even more weird and fucked up