No, not at all, because Section 230 has nothing to say about the scenario you are describing.

> No provider or user of an interactive computer service shall be treated as the publisher or speaker of any information _provided by another information content provider_

In your scenario Twitter is the provider of the information, so naturally they are liable for the legal repercussions of posting that information. Everyone already understands how this works intuitively, obviously when something illegal or otherwise legally significant is posted to the internet there isn't even a question of whether or not the posting platform is legally responsible for it as long as they are perceived to be taking reasonable steps to remove the offending content. If the site operators are posting the questionable content directly then obviously they are liable.

That's not what we're talking about though, we're discussing twitter having labled Trump's tweet as misinformation. I guess you're suggesting that twitter is the "publisher" of that warning and thus they are legally responsible for it, which is true, but there is nothing illegal about what they published so the hypothetical is moot.