Well, it was fun while it lasted. The professional relationship between billionaire Elon Musk, the owner of Twitter, and independent journalist Matt Taibbi hit a serious and possibly irreparable snag late last week following Musk's quixotic decision to suppress links to Substack.

Substack is a newsletter company with a stated commitment to the principles of broad free expression; as such, it is a preferred platform for many independent journalists, such as Taibbi. Twitter and Substack share a major financial backer: The venture capital firm Andreessen-Horowtiz has invested $65 million in Substack and $400 million in Musk-era Twitter.

When he acquired Twitter last year, Musk vowed to correct what he viewed as heavy-handed moderation policies akin to censorship, saying that the social media site should function as a sort of town square. With an eye toward demystifying the site's approach to content moderation, Musk gave several journalists—including Taibbi, Michael Shellenberger, Bari Weiss, Lee Fang, and David Zweig—access to Twitter staff's internal emails. This led to a series of reports, the Twitter Files, that helped explain why Twitter's previous regime had decided to suppress various accounts believed to be part of a Russian influence campaign. Unbeknownst to much of the public, Twitter had faced constant pressure from the FBI, the Department of Homeland Security, the Centers for Disease Control and Prevention, and other government agencies.