The claim that Professor Singer appropriates women’s voices because his name appeared first on a couple of bylines seems belied by the fact that Helga Kuhse and Katarzyna de Lazari-Radek (both women co-authors of his, in the 20th and 21st Century respectively) are listed first on all of the books they’ve written with him as far as I can tell. In his recent interview with Tyler Cowen, he assiduously mentioned Lazari-Radek whenever his work with her was mentioned.
While Dawn claims it is "important" that Singer filed a demurrer rather than contesting factual allegations in court, no one should update on that legal strategy. Almost any rational litigant would have done the same thing given the procedural posture.
For background at the 10,000 foot level, at the very early stages of litigation, you can file a demurrer ("motion to dismiss for failure to state a claim" in federal court) claiming that even if everything in the complaint is true, it doesn't give rise to liability. You generally cannot ask the court to dismiss the case at that point because the alleged facts aren't true. The reason is that if the plaintiff's legal theory is sound, she should ordinarily have an opportunity to develop the facts through discovery (document production, depositions, etc.) before the court addresses factual issues.
Discovery is time consuming and expensive, so if you have an argument that "even if everything you say is true, there's no liability here" and an argument that "what you say isn't true," it is almost always better to present only the former argument at the demurrer stage. If you start disputing alleged facts, you're implicitly telling the court that there needs to be discovery of the facts before the legal sufficiency of the complaint can be determined. Most people would rather not pay tens to hundreds of thousands of dollars, have to turn over documents, have to sit for a deposition, etc. Thus, they would file the demurrer even if they also think they could prove factual allegations in the complaint to be untrue.