I hope you come with a big van when you take in all the "i hope you die" commentators on YouTube. Policing the internet of all distressing talk is just a ridiculous idea.
I think content platforms like twitter do have a responsibility to make their spaces reasonably safe for their users. This means not allowing one user to make threats against another.
There's a difference between hoping bad something might happen to someone, and threatening to rape them, come round to their house and stab them or telling them you've planted a bomb on their car. Would you argue otherwise?
I would have been happier if it had been handled with an investigation and warning and not make it to prosecution, but as far as I'm concerned, the guy deserved some nontrivial inconvenience. I'm kind of ambivalent about the fact that the conviction was quashed.
He wasn't even sent to prison. He was fined. I don't think that's a wholly unreasonable way for society to say "don't do that".