Elon Musk basicly doing two “Sieg Heils” in his Trump inauguration speech is one of the scariest things I have seen. But it is consistent with what radical Trumpist vermin has been doing for a while. It serves two purposes:
1. Condition the supporters to accept anything you are doing.
2. Show to your opponents that you are so powerful that you can get away with anything.
He of course denies that it had anything to do with the connection to Adolf Hitler. But he obviously quite deliberately chose to do the salute BECAUSE OF the connection to Hitler, had it not been the case he would have apologised already.