What Tesla did with bitcoin could be considered market manipulation, and that's a serious crime considered by the US government. The fact that the company invested $1.5B and make it public that bring a lot of investors to bitcoin, and after that, we see how bitcoin has a crazy jump in the prize, and now they sold the 10% when bitcoin was on its ATH.
As a reference, I will leave this link:
https://www.fbi.gov/scams-and-safety/common-scams-and-crimes/market-manipulation-pump-and-dump-fraudSo, the question is, did tesla make market manipulation and you think the company will be charged for it?
I think this matters depends on an individual's point of view. Tesla only stated the truth that they invested on Bitcoin and never said anything else. They don't say Bitcoin will increase in x% or will be pump nor hype the market according to their gain. They just release a news that they had invested and there is no lie in it. If their reputation enable other investors to invest heavily in Bitcoin, it isn't Tesla's fault since Tesla never said directly to anyone to buy Bitcoin. The increase of price of Bitcoin is just a natural course of market when one reputable company invested on it.