Even as the long-running conflict between President Trump and Twitter will enter a new stage with Elon Musk acceding to ownership, a new antagonism is emerging between the maverick entrepreneur and a legion of European bureaucrats.  

In purchasing the social media platform he calls the “digital town square,” Mr. Musk has thrust himself into the maelstrom, with European regulators and Mr. Trump serving as the Scylla and Charybdis of the stormy digital seas the Tesla and SpaceX CEO will be required to navigate.   

New regulation is on the horizon in the Old World. The European Parliament and European Union member states have given a provisional go-ahead to the Digital Services Act, which would require tech platforms to install systems to aggressively moderate content or face billions of dollars in fines. 

In touting the legislation, the EU’s commissioner for competition, Margrethe Vestager, proclaimed “democracy is back.” The president of the European Commission, Ursula von der Leyen, has likewise hailed the DSA as ensuring that the internet “remains a safe space.” 

However, that safe space is being policed with increasingly sharp penalties. Violations of the law, which is set to go into effect in 2023 or 2024, could precipitate confiscation of 6 percent of annual sales. In a globalized world, American companies would be dragooned into compliance. 

Additionally, the largest companies — those with over 45 million users — would be required to pay Brussels a supervisory fee that could tally 0.05 percent of their global annual revenue for the law’s enforcement.  

“We are open but on our conditions,” another one of the DSA’s architects, the EU’s minister for the internal markets, Thierry Breton, has cautioned Mr. Musk, who calls himself a “free speech absolutist.” Mr. Breton warns that Twitter will “have to totally adapt to European regulations.” 

Mr. Breton went on to warn Twitter’s new boss: “Elon, there are rules.” For Mr. Musk, whose takeover of Twitter was pursued with off-script abandon, this veiled threat presages a likely conflict between a vision for Twitter that involves fewer rules and a regulatory apparatus that intends to impose more of them.

If Mr. Musk’s Twitter does not come to heel, Mr. Breton tells the Financial Times that the company will be “banned from operating in Europe.”     

While he must contend with Brussels, Mar-a-Lago appears likely to be heard from as well. For President Trump, Elon Musk’s purchase of Twitter is the best of times and the worst of times. 

Mr. Musk’s acceding likely means the end of the 45th president’s “permanent ban” from the social network that bills itself the “town square” of the media and political set. “Free speech is the bedrock of a functioning democracy,” Mr. Musk has said. 

Mr. Trump, unpredictable as always, has declared that even if Mr. Musk lifts the ban, he has no interest in rejoining the social media application. Mr. Trump told CNBC that he “was disappointed by the way I was treated by Twitter. I won’t be going back on Twitter.” 

Regardless of whether Mr. Trump joins Twitter, the takeover by the world’s richest man threatens to short-circuit Mr. Trump’s rebellion against Twitter’s reign, and render moot his efforts to conjure its competition. 

As long as Mr. Trump was a persona non grata on the platform, his passionate base presented an inchoate audience for an alternative.  

The numbers suggest that Mr. Musk has not only bought Twitter, but also swiped Mr. Trump’s thunder. His special purpose acquisition company, known as a “SPAC,” is down 44 percent since the news of Mr. Musk’s takeover was announced. 

This entity, Digital World Acquisition Corporation, is tied to Mr. Trump’s social media platform, Truth Social. That venture is now flirting with superfluity. 

As the tremors of Mr. Musk’s acquisition continue to be felt worldwide, it is clear that he intends to play by his own rules. In one tweet worrying about “de facto bias in the Twitter algorithm,” Mr. Musk asks, “how do we know what’s really happening?”