"I hope you die" is not a threat. You are equating utterly different things.
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".