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.

I take the and in his reply to infer he agrees something additional should be done. Whether his ultimate response for how to do that is adequate is unknown, since he didn't really elaborate on exactly what he thinks should be done. It could be he meant that to signify agreement with the suggested course of action in addition to agreement that there's a problem to be fixed.

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).

There are a variety of ways root can hose a system and many are recoverable without replacing hardware. Hard bricking a motherboard is a whole different league.