TBH he probably doesn't know he did it

Reason: "Blocking the U.S. Steel Sale Is a Perfectly Disgraceful End to Biden's Political Career - It's a disgraceful decision that serves as a perfect epitaph for Biden's political career."

The decision to block U.S. Steel's acquisition by Nippon Steel is the perfect coda to President Joe Biden's political career.

By intervening in the private business affairs of the two companies, Biden is demonstrating once again his expansive view of executive power, hubristic sense of government's ability to order economic affairs, and willingness to stretch the definition of "national security" to justify his big government agenda even when there is plainly no national security threat.

Those elements have been central to Biden's political persona for decades. Even as his charisma and mental facilities have failed, they remain. From his earlier support for the drug war, the USA PATRIOT Act, and Obamacare to his administration's attempts at broad student loan forgiveness and inflation-inducing Bidenomics, Biden has rarely been deterred by norms or laws that limit federal power or by economic good sense. If there's something Biden wants to do, he'll simply find a way to do it.

To be fair, I believe Trump also supported the merger block.