There's no possible comparison between Musk and Mamdani's gestures, at least from the perspective of someone who grew up in a region occupied by the Nazis during the war and had him grand parents deported.
Regarding EU politician support, it's really not what you describe. The politicians he's been supporting are the ones in the rightmost spectrum of the political chessboard in each case I've witnessed. There isn't a car I've witnessed where he supported someone center right, or left.
These false equivalences are dangerous.