I wonder the same, my theory is that this gesture is used both as a loyalty test and a way to further polarize society.

Making this gesture draws clear lines in society: those who say it was fine, those who say it wasn’t, those who don’t take a stance (ie the media calling it a “controversial gesture” or similar). So Musk & al now have a clearer idea of who stand where. It also cleaves those “for” and those “against” further away, solidifying their base.

Another explanation is this is part of the normalization of extreme rethoric and symbols. I doubt he could have gotten away with it ten years ago.

Yet another possibility, he did it on a whim and the neo-nazis like Bannon are now seizing the opportunity. It’s unclear how planned this was and how intentional the consequences were.

(And all might be true at once)