I am not making a judgement here at all and I'm making zero comments on Musk's ideology or character, only that he made a poor branding decision by supporting a voting base and politicians that to not represent the folks most likely to buy a Tesla.
You don't need to argue the intent of the salute; you can just see which candidates he supported and donated to.
(It's fine to debate policy on things like incentives, but that is at least part of the reason why we see China making big leaps here because the government has aligned the incentives with buyers and manufacturers to make electrification the default)
It's more a reflection on the Left at the time that businesses (let's not pretend this was just Musk) were forced to deal with those anti-environmental, anti-electrification, and anti-incentives candidates.