What motive does SpaceX have to block X though Starlink? Their assets are frozen, they're operating in Brazil for free.
I'm no lawyer but from what I gather there's two issues with Starlink, one where they had their bank accounts blocked to make them pay for Twitter's fines, which is highly controversial and they could appeal it, and one where they could lose their operating license for openly refusing the general order to all ISPs in Brazil to block Twitter. If they blocked Twitter and appealed on the quite reasonable grounds that they are different companies they would have a much better chance of returning to normal operations in Brazil.