Bill Ackman’s vendetta against Business Insider shows no sign of slowing down. After the publication produced a piece detailing his wife Neri Oxman’s alleged plagiarism, the billionaire hedge fund manager tweeted out several jeremiads (maybe that 240-character thing had a purpose) at BI and its parent company Axel Springer threatening legal action. Now he has written a 77-page demand letter that… threatens legal action if BI does not retract its article.

According to Ackman: “these individuals did not question that Neri and I had been defamed, but rather they explained that Axel Springer has been perhaps the strongest long-term supporter of the state of Israel of any media organization, and also an important advocate against antisemitism.” What began as a noble quest to address antisemitism on America’s campuses has descended into something rather petty. As one former PM might have said, it’s time for Ackman to put up or shut up.