It's not illegal to buy a stock and tell people you bought it. There are entire businesses whose model is "make an investment, and then tell other people why you made it hoping they will make the same one". This isn't criminal, it's good business practice.

The thing he got in trouble for with Tesla was for lying about about a takeover offer, which is criminal, basically because it's a type of fraud. This isn't that.

Not a lawyer, not legal advice, etc.