> I think some people are just irrationally upset about perceived threats to something that is very important to them.
Some opponents of systemd seem to think that a move to systemd is an irreversible move in the wrong direction -- that once a distro moves to systemd, there's no going back, because systemd is large, complex, and monolithic, unlike the simple and modular SysV init system. If one is strongly attached to Debian, and feels that the distro is moving irreversibly in the wrong direction, I can see why one would strongly oppose such a move.
It has nothing whatsoever to do with Linus.