I don't think you give this nearly enough weight.

It's not like Fox News or MSNBC at all.

Fox News and MSNBC wear their hearts on their sleeves: their whole reason to exist is to show their own content. Everyone can see how they present issues, so it's an incredibly easy job to demonstrate bias. Even if they aren't sued for making patently false claims like "fair and balanced" (unless you take the words to have no meaning whatsoever), they are clearly corporate endeavors and it's easy to document how they conduct themselves. There's no surprise.

But Twitter isn't like that. Twitter is not a corporate producer of content. It's a distributor of massively parallel content. It's extraordinarily difficult to tell anything about how Twitter works. Twitter is opaque.

The assumption is that Twitter is neutral. The value of Twitter is that it is neutral (it is a channel for you not for them). The statement is that Twitter is neutral, if we are to trust the statement of any company on anything where the counterfactual might hurt its bottom line. (Maybe we shouldn't.)

The difference between monolithic media being biased and Twitter pulling its stunts is the difference between a politician saying, "The other guy is going to take away your guns / medicare", and thousands of flyers for the other guy mysteriously disappearing.

I'm not sure why you're not more alarmed. Maybe you have a really strong assumption that "social media" is like "mass media", given that you compared Twitter to newspapers without apparent concern for some perhaps really important differences in the nature of the business and its role in society? Maybe you're only looking at the "undermining elections" angle (which I agree is tenuous) and not the "undermining the system that even makes elections a sane thing to do" angle?

A lot of stupid hyperventilating is happening on the Right, no doubt, but the core criticism that this is a fairly serious abuse of trust (and a significant attack on free speech) is, I think, entirely justified.

Meeting weekly with the FBI while secretly applying "visibility filters" to politically and socially relevant voices isn't a Nothingburger at all, unless you view 1984 as an aspirational manual for your society.

Of course it could be worse, but isn't this bad enough?