The OP is a bit misleading.
There was no "excommunication." Bishop Pivarunas wrote a letter-- I'm not sure exactly how widely it circulated, but it was at least disseminated in the midwest. This letter was published at CMRI chapels and it was not an excommunication. It was a brief summary of how Crawford's ideas are condemned (mainly by Vatican I, who says that the pope has no judge), and it concluded by saying that faithful who continue to attend his "masses" will not be administered sacraments by any priests under the spiritual care of Bishop Pivarunas.
Crawford has caused quite a bit of turmoil in the midwest (and elsewhere). When he was a seminarian at the CMRI he was clandestinely "recruiting" people and establishing a network among the laity to support him for when he decided to finally leave (he was dismissed from the CMRI, yes, but he knew that was coming if he came out as a Feeneyite, and the exact same thing would happen if he had been a seminarian at the SSPX, SSPV, or at Brooksville. There are no traditionalist clergy organizations who are Feenyite, thank God). So since he was dismissed he went off to Tennessee or wherever it is that Neal Webster is hanging out and got ordained by him-- maybe. Who knows if Neal Webster is a bishop? Crawford's own defense of his orders is a mess, and it doesn't at all attempt to defend Webster's priestly orders, which so far as I'm aware came from the FSSP and he was never conditionally ordained, which means he couldn't make a bishop even if the man consecrating him a bishop actually was one. Anyways, after Crawford went off to get ordained (which he didn't waste any time doing; he was out of the CMRI around late 2016 and showed up in early 2017 "ordained") he activated his sleeper cells throughout the midwest and there was a fairly noticeable exodus from CMRI chapels, including one chapel which he tried to have himself installed at (no dice, Laus Deo).
So there's the Cliff's notes history. Crawford, a man with doubtful orders and dubious doctrine, has been sowing discord among the faithful (his Feeneyism is not his only problem doctrinally speaking) and getting them to patronize him. Given that his doctrine is bad, his orders a mess, and everywhere he goes he leaves a path of disgruntled, agitated faithful, Bishop Pivarunas waited about two years and now he's telling faithful that if they want to go to Crawford they're not going to be able to come to the CMRI. Is that a good reaction? We can certainly debate it. It was obviously a deliberated and not hasty decision given the lapse in time between when he started causing problems and now. I don't have a problem with it; in fact, I think that many of Crawford's "faithful" near one of the CMRI chapels were only at the CMRI chapel because the local SSPX had already kicked them out for being Feeneyites. You're not going to find any traditionalist organization that suffers Feeneyism. To varying degrees they all condemn it. If anything, what the CMRI is at fault for is suffering Feeneyites for too long. For turning a blind eye to them and being pitiful and merciful toward them, even thought many of them aren't sedes, but because they had been run out of the SSPX.
Point being-- besides providing some background on the case-- Bishop Pivarunas didn't (and didn't even try) to "excommunicate" anybody.