The idea that some random particle from the unfiltered BALF "soup" is pathogenic *IS* the theory until properly proven otherwise. On the other hand, what I described is not theory, but a highly questionable process documented in the scientific paper claiming to have found "new coronavirus".

It is very compatible with other previous virology research in a sense that all of it is based on bad practices, where they extract RNA from random cell debris and then computer generate the sequences using special software. In that particular paper that you mentioned, they did not even try to prove pathogenicity, but in others they kill starved cells injecting them with BALF "soup" along with antibiotics and without performing any control experiments claim that it was the virus that killed them. Which is utterly unscientific.