Chinese censors incinerate entire run of a kickstarted Call of Cthulhu RPG sourcebook

Julio writes, 'Sons of the Singularity is a small RPG publisher. Last year, they kickstarted The Sassoon Files, a sourcebook for the popular Call of Cthulhu RPG and Trail of Cthulhu RPG. As a lot of publishers, theydid the printing in China. The same day that the print was finished, a Chinese Government decided that it was 'problematic', so they burned the entire print run.
Targeting foreign publications is a first, specially when it seems there wasn't anything problematic (the supplement was based on Shanghai but was respetful and documented carefully).
Will this be a new sign of Beijing tightening its iron grip or just a show of bravado with a small publisher used as an example?'

Don't want to seem alarmist here, but perhaps giving a veto over the vast majority of the world's manufacturing, media reproduction, printing, etc to the Chinese state might just turn out to be problematic in terms of free expression.