I would encourage you to watch the whole video of the incident, with sound, and then put your hand on your heart and honestly say you think that was a sieg heil. (but don't throw it to the crowd after)
It was not a coincidence that it looked like one. Nobody with knowledge of contemporary history would make a gesture that could be interpreted as "Sieg Heil" by mistake at an event that is watched worldwide.
I've watched it, many people have, and have still firmly concluded it was a purposeful action. It's debatable whether it was a true "I'm a Nazi" move or a "I'm a troll" move but the smirk on the face, the long, long history of trolling and antagonizing opponents, the previous comments from Musk that the left was calling him a Nazi, etc... all indicate that he intentionally did something provoking.
This is even more true for the latest copycats from CPAC, which show that the Fascist salute is being normalised and becoming a MAGA symbol. Think about that. Whatever Elon's original intent, the American right is now knowingly doing the fascist salute, not as satire but as a open sign of their politics and provocation to their opponents.
I watched the video with sound quite a few times. It was totally heil hitler salute. (Not to bring up the statement Elon made about how Germans should stop apologizing for holocaust. At that point even the anti-defamation league gave upon him. Elon is fascist to the core)
I don't understand why modern day Germans would have to apologise for the holocaust either, maybe I'm out of touch.
I also don't know why HN keeps these Elon posts up because they're always a shit-show of reddit-ness and I believe most other similarly high-conflict subjects would have been nixed by now.
I would encourage anyone who thinks it was not a Nazi sieg heil to go into work and do the exact gesture in front of your boss, and then report back here on what happens.