"Coming apart at the seams" means that entropy and dark energy will eventually tear apart the natural order that we take for granted. Complex molecules will deteriorate and all the stars will go out, depriving their satellites of energy.
The judgment of the badness of death and destruction is indeed subjective (unless we bring in my aesthetic reconstruction of objective morality, which is another matter). But that's not my anthropocentric judgment. It's part of the meaning of "accident," which this article analyzes.
I don't doubt the efficacy of objective causality. What I doubt is the blasé attitude towards it in light of the problem of induction. The weirdness is in a self-assembling natural order that simulates intelligent design. Elsewhere, I show in more detail what's monstrous about godless nature (link below).
You're strawmanning existentialism. Also, I don't follow any existential philosophy in its entirety.
http://rantswithintheundeadgod.blogspot.com/2015/08/is-nature-beautiful-or-monstrous.html