By the way, the Publisher vs. Platform discussion reggarding twitter, facebook, youtube and other has been had before. Including in US congress. And it was rulled then that they are platforms and not publishers.
As is, in most countries, platforms are not accountable for what users wrote on them, but they still can receive warrants to remove criminal content from circulation by authorities and that indeed does happen, and Kojima could very well seek that action with the law as it is right now, but I think it would not even be necessary because I'd bet all tweets with the incorrect news have already been removed or corrected by their very authors.
Notice, though, that in this scenario, the persons responsable for defamation is still exclusevely the posters. The platforms are just required to remove the content to be compliant with a legal rulling, but are not seen as responsable for the crime itself, just as an unfortunate 3rd party that got caught in the cross-fire so to speak.
Now I don't think the legalist argument is that interesting since these decisions can often be overulled and social-utilitarianism (with all the limitations of measuring and predicting that very subjective ideal) has about as much weight as technicalities of legal classifications of what constites publishers vs. platforms.
I'm way more interested in the spirit of the choices we make, the kind of phenomena and behaviour our systems insentivise vs. punish.
@DSalready already mentioned the nanny-state aspect of holding twitter accountable for every single tweet as if it was a publisher. When too much responsability is put on "higher-up" entities and authorities, the indirect effect is the infantilization of the individuals bellow, and the gradual increase in arrogance of the decision makers higher up.
Out of good intentions, you are asking for bureocrats and clerigy to constantly police everyone (including you and me) in ways that once established are much harder to disassemble. And there is no guarantee the bureocrats will do a better job than the individuals bellow. The bureocrats are humans themselves. Only difference is the bureocrat can hide behind an official "stamp of aproval" to tell you to shut the fuck up, and you cannot respond in kind. A flatter more equalitarian struture (self responsability, no holy-protector) avoids such power disparities (but it doesn't avoit others: such as more popular vs less popular individuals etc).
Secondarely, but I think even more importantly, it goes against the best aspects of the internet. Its an outdated, centralizing, gate-keeper-based mentality.
Wikipedia is the best enciclopedia ever devised because instead of relying way too much on a centrilized curating entity, it allows for more collaboration and self-regulation. If everybody thought the way you do, wikipedia would never have come to be.
Yes, wikipedia is flawed, but so are other publisher-centric publications too. But with wikipedia, whatever flaws are there are collectively OUR OWN fault too, since we all have the power to go in and improve it. Wikipedia does not fight missinformation with censorship, but rather: with Better information. Stop and think for a moment about how powerful of a psychological and cultural change of mindset that is.
None of the awesome platforms we use today such as twitter, youtube, instagram would exist in an environment of severe unilateral punishment dished out at everybody as the one you are suggesting. Your draconian system would not abolish dissinfotmation. It would kill off most information, good or bad, all together. Not even Beyond3D would be able to exist. I mean, I don't think anybody in their right mind would chose to host a forum in which any lunatic can come at anytime and invent that Shiguiro Myiamoto murdered JFK and get everyone involved sued that way. Would you?
New lies and missconceptiins will always come to be, no matter how many layers of official fact-checking staff and legal punishment you dish out. But I'd rather have the tools to fix those mistakes be in my hand, rather than in that of some opaque authority hidden multiple levels away from me.