Just because Elon buys a company, doesn't mean he will do something amazing. I get that people are expecting a lot from him because of the companies he owns and the weird personality he has, but at the end of the day he didn't really "achieved" anything himself, it was always people around him or people before him.
His first company? Merged with another successful company before being bought out and he was kicked at that point, tesla? Built way before he bought it, spacex? Dude has zero engineering education. So, twitter is just a social media where maybe he could actually do something, it is really uncanny how much people idolize him while he does absolutely nothing himself.
The fact his the man behind the idea of building SpaceX is already something, not all businessmen were able to do it not even NASA alone before. It takes a leader before something can happen. He can buy companies he wants provided the owner will allow him or he will be able to gather more shares. Sure he will do this to gain more access in social media but preferably for himself, businesses or for his crypto investments.