I disagree that these arguments contradict Pinker at all!
What Better Angels is most clear about is the thesis that violence has decreased with modernity. That point is not refuted by these abstracts, or their writeups.
And the secondary claim that large, stable societies are less violent is also not refuted.
What they do do is accept Pinker's argument implicitly and talk about a way of interpreting why it might be true.
That's an incredibly common pattern in science! As a paradigm becomes familiar and accepted, aspects of its founding assumptions get reexamined and reinterpreted. Why the various writers cast that as a refutation is a matter of guesswork--my guess is that it's good marketing for attention (a perfectly valid motivation).
Massimo Pigliucci (@mpigliucci) thinks that it also shows that Pinker "may be wrong about the causality".
But I disagree with that treatment of the term "causality". Better Angels is clear only on the historical trend, not on the causality (contra many of its critics, like Nassim Taleb, who suggest its argument is rigid), and suggests there may be interacting and dynamic forces at play.
These papers, as with Pinker, fundamentally only assert that less violent societies are less violent, that less violent societies tend to be more recent, that more recent societies tend to be bigger, that big societies tend to have extensive organization, etc.
Pinker's basic focus is on the constant need in ad hoc tribal societies for people to assert their potential for violence in order to defend themselves, vs. the lack of such need in modern large, liberal countries with business with their neighbors and presumption of security. The "scaling artifact" argument literally shows Pinker is correct about decreasing violence in society!