EDIT: By "necessity", I mean things such as GNOME (which is a very often used graphical shell in a majority of distributions) and udev (which is getting integrated into systemd, is used by most distros, and, bar Busybox's mdev or Gentoo's eudev fork, has no alternative) depending or planning to depend on systemd.
On one hand, personal and death threats are way out of line. On the other hand, he kinda rip what he sow. He could have done the same post without mentioning Linus and Gentoo for instance. When you put so much "energy" to push for a key component, don't be surprise by the push back. Especially if you're not willing to compromise. Yes, it can get out of hand, but that doesn't mean the push back has no ground.