Trump tried tweeting from official POTUS account, tweets immediately removed

That's pretty baseless, as they are not discriminating on the basis of political party or political affiliation. Romney's remarks aren't being removed, because he's a Republican who's not encouraging violently overthrowing the results of our elections.

Pretty sure you can remove people who have signed a contractual agreement that they can be denied service at any time.

    We may stop (permanently or temporarily) providing the Services or any features within the Services to you or to users generally. We also retain the right to create limits on use and storage at our sole discretion at any time. We may also remove or refuse to distribute any Content on the Services, limit distribution or visibility of any Content on the service, suspend or terminate users, and reclaim usernames without liability to you.

Section 4 of

https://twitter.com/en/tos

I think they're more worried about getting sued if their services are used to plan/incite a crime and they do nothing about it...

edit: civil suits are so easy to file, they probably don't want to risk 'wrongful death' type suits.

It will be interesting to see Republicans argue that their conduct on social media is an attribute of their party affiliation. They would either have to (1) argue that they weren't spreading fake news or inciting violence or (2) that spreading fake news and inciting violence is part of being a Republican.

To be more realistic, the State of Iowa is either about to learn a very expensive lesson about compelling private companies to host speech or they'll suit back and accept the necessity of these actions.

Banning discrimination on the basis of party for private entities is itself a 1A violation.

The protected classes in Iowa are "race, creed, color, sex, sexual orientation, gender identity, national origin, religion, or disability" (copied from §206.8(a) in the linked PDF). Political viewpoint is not a protected class [1]. It might qualify under "creed," but the typical definition of creed is generally tied towards religious beliefs rather than political beliefs, so I would not qualify it as such without a court case to back it up with precedent.

Of course, that is moot since Trump is a Florida resident who is physically present in DC, and we're talking about a service whose contract says you agree all suits will be handled in California, so Iowa does not have personal jurisdiction here.

[1] Political belief is not a protected class in most states, actually, including California.