Ahhh. That makes sense, and I understand the reasons for that limitation, I think. That law makes perfect sense the way you describe. Otherwise, there would be an endless "guilt by association" sort of scenario, and any association would bog down innocent people in criminal charges.
I've been through the criminal legal system in Canada (not guilty fwiw), and I have sisters who are lawyers who answer questions (granted, one is all mergers and acquisitions, and the other is family law). But I must say, all legal systems, while usually internally coherent, don't really make sense from the outside. It's incredibly opaque and couter-intuitive. Thanks to both of you. I think I understand the reason for that limitation.
Again not to turn this into RICO discussion but:
RICO was set up to target Organized Crime fuckery of the legal system by shifting a large portion of the burden of proof from prosecutors to defendants: once they make a case there is a criminal organization or conspiracy, once they prove you are member, it is then up to you to prove that anything you owned or are involved with has not benefited from your involvement in the criminal conspiracy. You can also be convicted of crimes committed by other member of the conspiracy, whether or not you had knowledge of the crime.
So to your twitter point:
Lets say there is washed up poorly aging former stand-up performer (that I won't deign to call a comedian) named Gathy Kriffin, and it is proven she is part of an organized group that encourages vigilantism and violence against people based on the color of their skin*. That means that if Gathy was proven to have, say, participated to a criminal degree in the provoking and organization an assault against the a highschool student (or the 12 year old son of a politician) that would mean everyone involved in the conspiracy could also be charged with that crime regardless of actual involvement. It would then also make the conspiracy a criminal enterprise, and all assets owned by members that are involved in the organization's criminal activities or benefit from association of criminal activities** could be seized.
So if Jack Dorsey was found to part of the conspiracy or knowingly aiding the conspiracy, Twitter could be seized. If he was not found to be part of the conspiracy, like Umbertos it would be safe.
(it also occurs to me you might be getting tripped up by capital-m Mob (structured criminal organization; aka mafia) and lower-case mob (band of unruly hoodlums). )
More applicable to this situation would be First Amendment limitations:
Shouting "Fire" in a crowded theater is not protected speech. Or more specifically, using speech to knowingly create danger for others, for no other purpose than creating that danger. (Shouting "Fire" in a crowded threater is obviously protected if you reasonably believed it was on fire).
You could argue that Twitter is willingly allowing this libelous speech which creates an unsafe environment for these kids, but the link here is tenous and would be very hard to litigate; you'd also have Pro-First Amendment protection organizations coming at you head on out of principal.
edit: American jurisprudence is set up to prefer allowing freedom of speech instead of disallowing. The reason for this is clear if you look at Europe. The founding fathers wanted to make sure no American would go to jail for teaching their dog to do a nazi salute.
America was intended to be a dangerous place for independent, strong willed, free-thinking people to do be free from small-minded powermongers. People who wanted safety and security could go back to Europe and be serfs for a king.
*Which in and of itself is a federal civil rights violation.
** Which is to say: if you are a mobster and use money from your mobster activities to prop up an otherwise legitimate business
