Earlier quoted context omitted.
He says "The ability to hose a system is certainly reason enought to make sure it's well protected and only writable to root." That looks like agreement that it needs something done to me. I took the followup comment to be a useful to on how to mitigate the problem until then.
Isn't it already only writeable by root? The request is to make it not even writeable by root without taking some additional action to make it writeable first. If I understand correctly, that bit you quote just describes the current situation.
In any case, the only thing clear to me from his statements is that he agreed that there was a problem in need of attention, which makes the response here somewhat baffling to me (although not as baffling as it should be. It's fairly easy to see how a lot of the animosity comes from feeling about systemd in general and Lennart in particular, especially since some people state as much, as if that has any bearing on his response in this instance).