The judge found that X Corp's argument exposed a tension between the platform's desire to control user data while also enjoying the safe harbor of Section 230 of the Communications Decency Act, which allows X to avoid liability for third-party content. If X owned the data, it could perhaps argue it has exclusive rights to control the data, but then it wouldn't have safe harbor.

"X Corp. wants it both ways: to keep its safe harbors yet exercise a copyright owner’s right to exclude, wresting fees from those who wish to extract and copy X users’ content," Alsup wrote.

Seems like a sound judgement. You can't have your cake and eat it too. If Elon Musk wants to own the data, he must also be liable for it.