per your articule
"Only he who has been
publicly declared a vitandus and denounced by name
by the Holy See is considered a vitandus (2258). "
vitandus/ from
uk.ask.com/wiki/Vitandus
A vitandus (Latin for “one to be avoided”) excommunicate was someone affected by a rare and grave form of excommunication, in which the Church ordered, as a remedial measure, that the faithful were not to associate with him “except in the case of husband and wife, parents, children, servants, subjects”, and in general unless there was some reasonable excusing cause.[1]
It thus imposed a form of shunning somewhat similar to Jewish cherem.
Since the coming into effect of the 1983 Code of Canon Law, this form of excommunication is no longer envisaged in the canon law of the Catholic Church. The 1917 Code still included it, imposing it automatically (a latae sententiae excommunication) on anyone who did physical violence to the Pope himself,[2] and declaring that with that exception, “nobody is a vitandus excommunicate unless the Apostolic See has excommunicated him by name and has proclaimed the excommunication publicly and in the decree has stated expressly that he must be avoided”.[3]
The distinction between a vitandus and a toleratus (“tolerated”) excommunicate was introduced for the first time by Pope Martin V in 1418.[4]
since this would not apply to the normal everyday person that leaves the church and starts
going to another religious body having mass said for a them would be fine.