I think the line is typically drawn at any human intervention. I doubt many humans consider steaks to be a naturally occurring phenomenon.
Now, there is a secondary fuzzy notion of "artificial" typically used in relation to "chemicals". I don't think that definition stands up to most serious scrutiny, and is at any rate unrelated to this article.
That's exactly what's being—albeit atypically—advocated for here: That even steaks are a naturally occurring byproduct of humans and cows because humans and cows naturally exist.
Sure, but then of course absolutely everything is "naturally occurring". Plastic is a naturally occurring substance, computers are naturally occurring objects, C++ is a natural language. Perhaps then only miracles from God (for those who believe in such things) are unnatural?
Plenty of people do not believe the conceptualization of a natural/synthetic divide does any good. There are entire subsets of philosophy, feminism, cyborg theory, etc. which talk about this.
Now, there is a secondary fuzzy notion of "artificial" typically used in relation to "chemicals". I don't think that definition stands up to most serious scrutiny, and is at any rate unrelated to this article.