There are always extremes like that, even when dealing with the most innocent topics you could imagine. People can even react similarly with death threats over a change in cartoon TV show that they didn't like. In any sufficiently large community you will find some small percentage of such people, it's nothing exclusive to init systems or even tech as a whole.

And it's absolutely not "Poettering is a prominent, controversial person, therefore it's OK"! It's never OK. It's rather "Poettering is a prominent, controversial person, so he should be at least prepared for that and not act like he's surprised".