I don't recall ever reading a rejecting peer reviewer for one journal calling out the same work accepted in another ("peer reviewed") journal. Before the web, I guess there wasn't much for a reviewer to do other than complain to their peers. Now the low quality journal is called out in public. And a rejecting peer reviewer calling out the author for ignoring direct contradictory evidence against their work. The threat of breaking peer review anonymity is now a force to be reckoned with.
I do not see how this article poses a threat of breaking peer review anonymity. The only anonymity broken here is the author's own, only in this particular case, and after the fact. What is the purpose of reviewer anonymity? It protects the reviewer from being pressured into accepting a paper (and to protect science from that happening), which is not a risk here, and it prevents reviews from turning into long-running disputes about the validity of a rejection, but in this case, the issue is one of the authors willfully ignoring objective, valid and significant objections to their work.
People often write "Comments" in the same journal that address a work's shortcomings. This can be the referees who are ultimately over-ruled by an editor, or any other interested reader.
