I'm in not two but several minds about Musk's 'salute', having seen it several times, and heard that he was saying 'Thank you' to the crowd at the time.
I also try not to jump to the most extreme conclusion BUT...
every time I look at it, there's some shocking in the horribly-familiar form taken by what is claimed to have been a friendly wave expressing heartfelt thanks to an adoring crowed. Not once but twice.
What was he thinking? What made his arm 'wave' in that way? Was there a subconscious intention? Who happily 'waves' to friends with a stiff arm and hand extended outwards?
Of course now he's gone and done it, there has to be a 'Nazi salute? Pshaw! It was nothing of the sort! Don't be silly!' response from the Trump camp, but it was very unsettling gesture by Musk, intentional or not, and I can't unsee it.