So I bristled at this too, but then I read the interview and tbh I don't see any reason to be pissed at Schneider. He never uses the phrase "liberal bubble" or anything like it—that's all the interviewer. And the response quoted below is about attracting users whose primary interest isn't politics.
The VergeBluesky's new CEO Toni Schneider on the platform's reputation for being a liberal bubble: "Yes, we definitely want that to change. It is already changing. It certainly wasn’t designed to attract one specific group of people."