On Thursday, ten days after revealing his 9.2 percent stake in Twitter to the public, Elon Musk delivered an ultimatum: either the board accept his offer to buy the company for $43 billion and take it private, or he’d “reconsider” his position as a shareholder. Such an acquisition could have huge implications for how we communicate online, and the entire affair presents troubling questions about the power Musk is able to exert over our society.

For all its problems, Twitter is central to cultural and political life in the United States and beyond, and Musk has long been one of its most prominent users. He wields it to preach to his adoring supporters, slam his critics, manipulate financial markets, and provide the media with fodder for endless clickbait. But his attempt to use his power to capture Twitter and reshape it for his own ends is serious cause for concern.