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

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.