The much more likely hypothesis in my view is that he was helping Trump because of personal conviction (only in small parts motivated by naked self-interest).
You should expect rational billionaires to tend politically right out of pure self-interest and distorted perspective alone; because the universal thing that such parties reliably do when in power is cutting tax burden on the top end.
So this isn't so much of an assumption, as taking him at his word.
He used to be quite charismatic, I believed him up until about 2017 or so. Then I figured he was just a bit greedy and maybe money got to his head but still a respectable innovator. However during 2020 or 2021 (I don’t exactly remember) he started to get quite unpleasant and making obviously short-term decisions, such as relying only on cameras for self driving because of chip shortages but dressing it up as an engineering decision.
You will basically never hear another CEO of another publicly traded company say this. I just don't believe that the same person who cares so little about his stock price that he sends a tweet like that (and the stock dropped 10% on it) also is making fraudulent statements to inflate the price. A better explanation is that he just says what he thinks without regard for the stock price, which is also something you won't see any other CEO of a publicly traded company do.