The difference is that murder is not prone to sybil attacks. You could literally mass-automate doxxing and swatting if you wanted to. Like imagine that you just had a bot that just scraped PII from a website, purchased phone numbers off the DN, and then used text-to-speech to call in a bomb threat. You can conduct this attack anonymously from the other side of the globe.

In order to murder someone you would physically have to visit them and try not to get killed yourself. Anyone can defend against murder, but literally no one can defend against swatting. There is literally nothing you can do to legally prevent yourself from being swatted.