I'd have thought so.
For one, a brain teaser I can answer after about 1 second isn't really a brain teaser. Since I'm definitely not smarter than anyone who already passed through the rest of the SpaceX interview process, this would be too easy.
Second, brain teasers are stupid, I agree with Musk there. I can only imagine maybe I'm overcome by anxiety talking to Elon Musk himself, not just the CEO of a company I would like to work for, but a billionaire genius. So maybe thanks to interview anxiety I am unable to come up with the obvious answer that moment - would that make me a worse software engineer? I'm interviewing for an engineering position, not a PR gig.