Either Bechly didn’t read the article, or he’s deliberately mispresenting the authors. The former seems unlikely given that he quotes the paper and refers to their results.
Bechly dedicates a whole section to the subject of “Incomplete Homework”, wherein he accuses the authors and other scientists of “not doing their homework” when it comes to the presence of cholesterol in non-animal species:
Paula Welander, a microbiologist at Stanford University, who was not involved in the study, said in an interview that “The study is based on the assumption that only animals create cholesterols, which … is fair with the current data but has the potential to change as we learn more about the many forms of life on Earth” (Wei-Haas 2018). Well, apparently the scientists did not really do their homework, because we already positively know that this fundamental assumption is simply incorrect…
He goes on to list several examples of cholesterols found in protists, fungi, choanoflagellates, etc. Did the authors actually overlook this? No.
Bechly cited 5 papers: Gonçalves Boëchat (2005), Kodner et al. (2008), Bühring et al. (2009), Weete et al. (2010), and Behrman & Gopalan (2005).
In their paper, Bobrovskiy et al. cited 2 of those papers (Kodner et al. 2008 and Weete et al. 2010), and 3 others: Najle et al. (2016), Gold et al. (2016), and Grabenstatter et al. (2013). All on the subject of non-animal cholesterols. It’s simply dishonest for Bechly to say the authors “didn’t do their homework” when they clearly cited and discussed these papers.
The relevant passage from the original paper:
Using the remarkable steroid patterns of the fossils, it is possible to test the position of dickinsoniids on the phylogenetic tree. Lichen-forming fungi only produce ergosteroids, and even in those that host symbiotic algae, ergosteroids remain the major sterols (29, 30). Dickinsonia contained no or a maximum of only 0.23% ergosteroids, conclusively refuting the lichen hypothesis (7). The groups of rhizarian protists that include gigantic representatives (Gromiidae, Xenophyophorea, and other Foraminifera) and their retarian relatives all produce a complex mixture of sterols, with cholesteroids comprising 10.3 to 78.2% of the mixture, ergosteroids 4.9 to 43.0%, and stigmasteroids 7.2 to 60.1% (table S4). Moreover, rhizarian protists may produce C30 sterols (24-n-propylcholesteroids) that can form a notable (up to ~20%) proportion of their total sterol content (31). By contrast, in most Dickinsonia and Andiva extracts, C30 steroids were below detection limits. Thus, the steroid composition of dickinsoniids is markedly distinct from steroid distributions observed in Rhizaria, rendering a protozoan affinity of these fossils extremely unlikely. All animals—with rare exceptions, such as some demosponges and bivalve molluscs—are characterized by exclusive production of C27 sterols (32, 33). The closest relatives of metazoans, Choanoflagellatea and Filasterea, produce 90 to 100% and 84 to 100% of cholesterol, respectively, and contain up to 16% ergosteroids (34–36). Although the sterol composition of some choanoflagellates and filastereans falls within the range observed for Dickinsonia and Andiva, they are unlikely precursor candidates because these groups are only ever represented by microscopic organisms, leaving a stem- or crown-group metazoan affinity as the only plausible phylogenetic position for Dickinsonia and its morphological relatives.
The relevant context here is that the authors were specifically testing the animal affinity for Dickinsonia against other hypotheses of a lichen fungi affinity or a giant protist affinity. By ruling out lichen fungi and giant protist affinities, the only remaining plausible option is that Dickinsonia is an animal. The only other option is that the cholesterols are some kind of contaminants from other organisms.