It's the internet. If you disappoint people on the internet, depending on how many pay attention to you, you are going to get death threats. The more people that pay attention to you the more likely you are to receive a death threat. Lots of broken people out there. It's ethically wrong to do it of course and we shouldn't accept people doing it. We shouldn't just throw our hands into the air and accept it. But other than doing what Andrzej Zawadzki did by speaking up about it, only better mental health, and social/legal repercussions for death threats is going to solve this problem. Remember if there is some problem in wider society, it's going to be a problem on the Internet as well especially with a bit of anonymity.