Most of what he's complaining about is undeserved (hiring a hit on him, WTF?) but he's not exactly known to be very diplomatic in his communications. He is, with a heavy hand, changing the fundamental landscape of a lot of people's favorite OS. This is upsetting people, in a big way in some cases. Again, constructive criticism is the way to handle dislike of systemd and his other projects, not death threats or even simple, juvenile insults.
But he shares some of the blame when it comes to the vitriolic nature of systemd discussions. He can't just brush off a large percentage of the community and not expect people to get upset.
What blows my mind is that every single major distribution seems to be hopping on the systemd bandwagon. I'm looking squarely at Debian. The short time systemd (relatively speaking) has been around and has been worked on and debugged does not justify it's inclusion in a system that's known for stability and correctness over latest/greatest.
Oh well, for me it was the kick in the head I needed to finally getting around to 100% embracing *BSD as a server system and not as something to play around with in my free time.