And why is that a bad thing? Trending blacklists are a standard moderation tool, basically every social media platform uses them nowadays. Without them, bad actors can game the algorithm to get their spam promoted through the trends system.

The fact that moderation tools exist does not imply that they are being used for political censorship. None of the screenshots of "search blacklisted" accounts from the leak showed any evidence of it being used on actual people, they are all random alphanumeric usernames with more reports than tweets.

In fact, the opposite is true. In 2018, when the feature was first rolled out, it was found to be catching several notable conservative commentators because their tweeting behavior is hard to distinguish from trolls and spambots (wonder why...), so those people were explicitly whitelisted so that they would appear in searches and trends despite their bad behavior.