IMHO this is entirely justified, I tried Bluesky for a couple months and I found the same thing; it's an echo chamber of american liberal extremism (not that it's bad; again, not trying to make any political statement here). I happen to agree with a fair bit of what they say, but not everything, and, while not commenting myself, I saw first hand anyone that isn't fully on the liberal train for every single little thing is declared a maga fascist.

How does people disagreeing with you become a lack of diversity of thought?

You have your thoughts and other people disagree. That is diversity.

If you mean "I want more people to broadly agree with me so we can talk about the small stuff we disagree on" then fine, many people on social media want that for themselves too. But don't dress it up as a desire for diversity while attacking the other people who want it as sheeple in an echo chamber.