While it is true that the First Amendment indeed allows people to say whatever they want, it does come with a few restrictions. Just as you cannot yell "Fire" in a crowded theater that is not on fire, so too you cannot post libelous information or impersonate another person. In the cases when a person who is known gets a fake account made in their name which is not obviously satire and therefore protected speech, then that account should be terminated. While Twitter is at it, they need to do a better job of getting rid of spammers and fake followers that inflate people's perceived worth.
No, I don't think that Twitter needs to do more to deal with misinformation. People should be able to say what they want on Twitter, and this includes lies. In turn, it's up to those reading these tweets to make a judgment on whether or not what they are reading is true.
Unless under oath for a government trial or hearing, pleople should be able to say whatever they choose. In the case of Twitter regulating what thier users post, I feel that Twitter should have no obigations for regulating the accuracy of information provided by there users. I do believe that Twitter has the responsibility of making sure that their users coply with the minumum standards provided by the FCC as far as inappropriate materiall
No, I do not believe that Twitter needs to do anything to deal with misinformation. Determining if a particular tweet is factual or not should be the responsibility of the user. If Twitter becomes the arbiter of truth on its service, that's tantamount to censorship. Even if it's entitled to do something about the level of misinformation, the extremes it would have to go to combat it would make Twitter far less valuable to its users.
Twitter is still a relatively new form of communicating, and as such I don't see the need for restricting what people choose to say in "dealing" with misinformation. I think that each twitter "receiver" should deal with twitter information as he/she sees fit, and if one doesn't like it one can always choose to not partake. If really bad or hurtful misinformation is given out then a lawsuit should happen.