I believe it stems from Charlie Talley's statement in an old (2006) Brewing Network interview when he described what makes StarSan unique. As he explained, it will kill in the presence of organic matter. If I recall, the context of this statement may have been in close conjunction with a question about the differences between Star San and Iodophor. That may have led to some confusion. But the short of it is, that is is likely one of the sources of the information.