So, first, the entire thing is an affront. To his credit, the preamble that lays out why he wants to do this is pretty honest: he doesn't like their ideology. Against that backdrop, the entire thing is as blatantly anti-1A as Obama's effort to use the CDC to "clarify" whether "gun violence" is an epidemic is anti-2A.
When you start from a specious premise, you generally get an invalid conclusion.
Now, that brings us to the practical effect of it - and chip, bring your risk mitigation hat.
Pre-EO, the conversation with someone hosting content had immunity as the foundation. Good faith enforcement of reasonable rules and documentation of how that was done made it pretty safe. (Laymen's terms, there.)
Post-EO, the solidity of that foundation is in doubt. If someone is spending $5k (conservatively) for content hosting for a hobby and there was little risk of liability, then that's no big deal. And if it generates some revenue to offset the cost, then that's great. If it breaks even, that's a good year.
Now, that $5k spend could turn into thousands of dollars of expenses (maybe tens of thousands) if some .gov functionary doesn't like what is being said.
None of this has anything, at all, to do with what the social media platform says. It has to do with the social media platform censoring and editorializing within the content of its users.
Trump is not complaining about @Jack or @Twitter tweeting anything at all, whether critical of Trump or otherwise. Trump is complaining about Twitter shadow-banning users, using ideological bias to throttle, suspend, and ban users, and modifying user content (specifically, Trump's) in an editorial manner.
The entire 1A rubric is based on limiting government to content-neutral rules. This upends that. The content is the target.
No, it isn't. Social media platforms are fully empowered to become publishers. All that this EO does is threaten to remove section 230 liability protection from platforms that choose to be publishers.
And the Fairness Doctrine was always a bad idea.
Again, this has nothing to do with the Fairness Doctrine. In fact, even in invoking the Fairness Doctrine, you are implicitly admitting that what Trump says is correct. Why? Because the Fairness Doctrine has to do with the content produced by the platform; thus, in invoking the Fairness Doctrine, you implicitly admit that the content is the platform's content and therefore by definition not the users' content. And if the content is the platform's, then the platform is not a platform, but rather a publisher.