If Hacker News is about the tech industry then we need to see the tech industry clearly, warts and all.
We cannot run away from it. We cannot memory hole it.
HN isn't "about the tech industry" per se - its mandate is to discuss topics of intellectual curiosity. See https://news.ycombinator.com/newsguidelines.html. Celebrity troll moves (or whatever this is) don't fit that bill, so in this case I'm inclined to agree with the users who flagged the story.
In terms of ethics, if the intention is to generate outrage in order to generate views and media coverage, does media coverage help or harm? Research on violence has has reached a fairly strong consensus that symbolism and displaying of cultural values is a major contributor for continued violence and conflicts. What should be the most effective (and ethical) strategy in reducing such display?
Watch this at 00:35. Debunks your entire point about "the look" with Hitler doing the salute exactly as Musk did it.
I'm from Switzerland / Swiss German and maybe we just watched way more WW2 docs in high school and had more exposure to the various ways a Nazi salute can be done, but across the German speaking sphere we all saw this as a Nazi salute. In this variation it was often done with hand on breast during "Sieg!" and then the extension with "Heil!".
The many published ww2 documentaries do indeed shows some variability in the Nazi salute, just like that youtube video you linked. The Wikipedia article (https://en.wikipedia.org/wiki/Nazi_salute) definition and their linked sources do not include the "hand on heart" part, which may indicate how common different versions are. The added "My heart goes out to you" statement to it is also seems like an very uncommon addition. A question we could ask is what people in the rally interpreted the gesture as in the context of the whole speech. Did they see it as an variable form of the Nazi salute, or did they interpret it as a gesture of gratitude?
Gestures has a natural ambitiousness in them. A person taking a knee in front of a king is different from a person taking a knee in front of a significant other and asking their hand in for marriage. The context and additional variability (like saying "do you want to marry me") changes the meaning of the gesture. In order for it to be one or the other the whole picture, context and gesture, need to align.
If the discussions is about ethics and symbolism we should also look at the ethics part. Political rallies are seemingly about displaying symbols and generating boundaries between in-groups and out-groups. If the gesture was intended to be an ambiguous Nazi salute in order to ignite controversy, we can look at what the consequences are. The in-group feels attacked, while the out-group becomes a threat for which the in-group can rally against. This strengthen the bonds of the in-group. It also increases political violence and instability, with both group "othering" each other. By instantly and publicly distance himself from the others interpretation, there is a gain of presenting themselves as the "true" anti-nazi and friends to Israel, especially now in the context of the current war in Gaza. This kind of political maneuvering is not that uncommon in far left and far right. Political researchers and analysts often remark that this create a problem of actually identity what the movement actually believes in, since the message is not in the actually words (or gestures), but rather in the intended outcome. The ambiguousness also create an environment that invites more extreme members which can be used to gain votes, or to kick out when there is political points to be gained.