Twitter is neither good, nor bad. It's a platform, and given its size, most of what happens on it is completely banal.
Twitter is also not a public utility, it's a private business whose owners have the right to manage it as they see fit, within the bounds of the law.
The problem here is that Twitter has become far more important as a nexus for political communication and news than it should be. But television is also an avenue to spread hate, fear and divide people. So are newspapers. So is radio and the telephone. Every form of mass communication carries that potential - plenty of riots have been started with just pamphlets and word of mouth. Twitter is just one site on the greater web, and the web magnifies the rate at which information of all kinds spreads. Get rid of Twitter, or censor it, and you don't actually change anything but the specific channels through which information flows.