Twitter serves as a mass media communication platform with 500 million users. There was never a comparable means for public figures to share information directly to the public without traditional media as the filtered vehicle. No waiting for a scheduled interview, no calling for a press conference, no dependence on anyone to share your quotes with the masses as you want them.
For years now, they've censored, shut down, blocked, and banned Conservative figures for violations of "Terms of Service." They have blocked and deleted news stories from major outlets that paint leftist public figures in unfavorable light. They've slapped warning labels on tweets that didn't support preferred narratives. In a final stupid move that may be remembered forever, they banned the account of a satire website.
Meanwhile, no such action has ever been taken against the producers and amplifiers of inflammatory leftist hoaxes and lies for years. Antifa outlets have retained their accounts. Public figures spreading anti-white and anti-semitic bile have retained their accounts. Users who comb social media to hack and dox others through Twitter have retained their accounts.
Sure, this is where your strawman about "private company/1st Amendment/doesn't apply" gets introduced, which you obviously know isn't the real complaint. The issue has been the uneven application of the aforementioned Terms of Service to drive a one-sided narrative. It's the biased manner in which users and information are treated with zero transparency.
The Elon Musk purchase is celebrated out of hope that a public forum -- which, like it or not, Twitter has become -- will be open to all users in the same way. And that's all it's about.