Fr. Feeney didn't go to Rome and this disobedience was the source of his excommunication. There is something afoot here. Some key piece of information is missing. Did Fr. Feeney ever, in one of his writings speak of his reason?
Any chance he never knew of the request to travel to Rome?
Any chance the request arrived after the deadline to appear?
Montini was behind a lot of this so, really, every benefit of the doubt should go to Fr. Feeney until proven otherwise. My reason for saying this is upon Fr. Feeney's death, and in the Catholic world at large, the believed reason for Fr. Feeney's excommunication is that he proclaims that those outside the Catholic Church cannot be saved. Well, we all know that EENS is Catholic dogma.
My belief at this time? Fr. Feeney was the fall guy. And, if he was disobedient in going to Rome (which is not related to his support for a Catholic dogma) then that was the excuse for the excommunication and now the modernists can act like EENS is no longer dogma.