For anyone confused by this headline, there are two trials this judge is considering for X
[O'Conner] was overseeing two lawsuits filed by X and recused himself from only one of the cases.
This isn't the new case about the "illegal boycott" O'Conner has recused himself from that trial (likely) because he also owns stock in Unilever, one of the defending companies
The judge's argument is that Tesla, which he owns stock in, isn't a party in the suit against Media Matters, just X. It's a pretty stupid argument, but he wouldn't be able to hurt Media Matters if he recused himself.