FWIW this is only thematically related, the order concerns the distinction between immune or non-immune activities under Section 230.
If you publish something defamatory on your blog, and you operate it, you may be liable. Section 230 is there to say that if a website merely retransmits your publication, it is not liable for it, so if you publish that same defamatory statement on Facebook, Facebook is not then liable.
However, the argument with the executive order is that if you exercise a level of deliberate control over the content beyond some threshold, or you augment expression (like Twitter did the other day, adding links to contrary opinion pieces next to the President's opinion), you effectively become a publisher of that content.
It's not a completely ridiculous idea either. Consider how diverse the expressions published to Twitter are; at some point it's not that different to choose not to publish some expression, than to express the complement of that expression yourself.