According to the article, in a recent shiur, Rav Moshe Shternbuch paskened that one cannot count a moiser as part of a minyan, calling moiserim people who have been reporting to the government on illegal minyanim or yeshivas functioning in ways that are against the health regulations.

Rav Shternbuch says there is no hetter to report this infractions to the authorities and this does not fall into the category of pikuach nefesh. Reporting to the authorities can only be done in exceptional cases, and only after warning the person or people and each individual case must be discussed with a rav examining the details of the specific case.

Rav Shternbuch added that anyone sick or carrying the illness must stay away from others and be careful.

That is interesting on its own, but it is especially interesting light of a psak from Rav Moshe Shternbuch himself from several months ago saying that one is obligated to report to the authorities on people breaking the health regulations, after warning them if possible in beis din or via the city rav. People cannot decide for themselves but must consult rabbonim and poskim on such matters, and it doesn't depend on what the authorities say, as they themselves keep changing their opinion regarding what is ok and what is not.

While there he is mainly referring to reporting on sick people who go out, he says it is an obligation to report on anyone endangering the public, and that could easily include illegal minyanim. often it has been found that illegal minyanim have had people with corona davening in those minyanim, spreading the infection to others in the shul. One could easily say that according to Rav Shternbuch, such a minyan is dangerous to the public and can be reported (after a proper warning).