Hitler says otherwise: https://www.youtube.com/watch?v=9tlenyBWs4w&t=88s
Says it twice: https://www.reddit.com/r/facepalm/comments/1i68puj/have_we_l...
In what way was Musk not doing a fascist salute?
Unfortunately, this isn't a one off connection. For instance, search Musk and the AfD.
Eventually you see enough associations between a person and who he sympathises with and you have to ask some questions.
The "roman salute" (which was invented by Italian fascists and not the Romans) is the same thing as the Nazi salute.
https://en.wikipedia.org/wiki/Italian_fascism
https://en.wikipedia.org/wiki/Fascism
So ultimately you've agreed that Musk did indeed do a fascist salute.