Twitter is capricious with its bans. It bans people for saying offensive things, but doesn't ban them for saying threatening or dangerous things.
I abhor hate speech, and I actually support my country's ban on it. I believe speech can be weaponized; advocating for the extermination of a person or people on the basis of race or orientation or whatever shouldn't be protected speech. (Don't argue with me about this; I don't care what you think in this regard. I'm just giving this preamble as context, not to invite any discussion on the matter. I mean, post if you want, but I'm not going to read any of it.)
The problem with Twitter is that because they're so useless on their own and haven't allowed anyone to make useful tools for the service, people that I *do* want to hear--usually women--are driven off the service because of the unending firehose of rape and death threats. Police don't take those seriously, and neither does twitter, and so the system becomes unusable for anyone at the receiving end of that. I don't think that's an acceptable use of a service.
IF Twitter had provided appropriate tools from the beginning (shared block lists, tools to filter out threats and random hateful garbage, etc.) this would all be a non-issue. The all-speech-is-free crowd could go off and do what they want, and the people that are just trying to live their lives without hearing how they should be raped to death could ALSO use the space as they want. Instead, Twitter lashed out in all directions at none, ineffectually banning people but not making the system any better for anyone.
If you're going to provide a platform for free speech (and for twitter, I fall on the side of more speech being better often because it means repressed populations may actually get heard), you also need to provide tools for some people to make sure they only have to hear what they want to.