Ah there is an update. The retraction notice has been published on the journal's website.
The bolded bit is important - seems Manchester were completely unaware of this publication. I imagine he'll be in serious trouble for linking it to their university without approval.
---------
Having reviewed editorial and peer review processes in relation to this note, the Journal Editors have concluded that there was a lack of clarity and hence ethical scrutiny at the time of the initial submission. This was particularly so in relation to institutional location and position, and ethical review of the work. While the Journal has systems in place to flag ethical concerns raised by article submissions prior to review, those same systems do not fully extend to note submissions. The two peer reviewers who considered the note did not raise ethical concerns in relation to the method and material in their reviews.
The author has now explained that the work described in this note was carried out as a piece of independent research in Germany, without institutional ethical oversight. The author stated that they followed professional ethical guidelines for their discipline, including the primary injunction to ‘do no harm’. The Editorial Team notes that such principles also refer to the need for the thoughtful consideration of potential unintended consequences of research, and the need to weigh competing ethical obligations.
The Editors are mindful of arguments that moral offense generated by the publication of the note provides problematic grounds for the censoring of scholarship. However, the Editorial Team recognises the argument that the note legitimizes sexual activity involving sexually graphic illustrated images of children and young people, both as an activity in itself and as a research method. Such arguments make the note highly problematic due to the potential to cause significant harm.
The Journal Editors believe ethical conduct and oversight in relation to research, method, methodology and publication is not a single event, but an ongoing process with shared and overlapping responsibilities between the author, the academic institution(s), the journal, and the publisher. On reflection, due to the potential for significant harm caused by the publication of this work compounded by ethical issues surrounding the conception and design, the Journal Editors have made the decision to retract and remove the note.
The Journal Editors and the Publisher sincerely apologise to readers who were negatively impacted by the publication of this work.