You are distracting from facts with speculations and trolling FUD. I refer to what is known and has happened, you are speculating on what is not known.
Your claim is an appeal to emotion trying to build support for a position the Linux community has largely rejected. Starting with the goal rather than looking unemotionally at the facts means that you’re confusing your goal with the attackers’ – they don’t care about a quixotic attempt to remove systemd, they care about compromising systems.
Given control of a package which is on most Linux systems and a direct dependency of many things which are not systemd - run apt-cache rdepends liblzma5! – they can choose whatever they want to accomplish that goal. That could be things like a malformed archive which many things directly open or using something similar to this same hooking strategy to compromise a different system component. For example, that includes things like kmod and dpkg so they could target sshd through either of those or, if their attack vector wasn’t critically dependent on SSH, any other process running on the target. Attacking systemd for this is like saying Toyotas get stolen a lot without recognizing that you’re just describing a popularity contest.