Any opinion that theoretically forces one to separate oneself from other traditional catholics is an evil fruit of said opinion. When this opinion leads to condemnation of other traditional catholics or causes one to view other traditional catholics with suspicion and/or contempt, it is another evil fruit. Any opinion that causes one to remain away from the sacraments, all else being equal, is yet another evil fruit. This opinion, when adhered to with pertinacity is involved with many injustices. It turns our understanding of what constitutes communion on its head by essentially adding what is extraneous to the content of divine faith. All matters are judged in light of this opinion, it becomes the operative norm while creating a set of entirely new (fabricated) problems, e.g. what do we do with the 1962 missal, the saints, Fatima, etc.
It is a most pernicious error when dogmatized. When it is not dogmatized, the tension is too great for the mind thereby resulting in either abandonment or militancy.