The excommunication was lifted in 1972. Your accusation that it is invalid is a denial of the authority of the Catholic Church. The reasons for the lifting of the excommunication are irrelevent. The Church does not need to justify its actions to you.
Canonically the grounds for excommunication were dubious, but needless to say, if valid, he was fully reconciled Petr Vere (canon lawyer) fully investigated the issue and he does not hold the Feeneyite position:
“1) There is no question Fr. Feeney died in full communion with the Catholic Church. Pope Paul
VI lifted Father’s excommunication while Father was still alive, and there is no evidence that
Father recanted his understanding of EENS, BOB, or BOD. The actual lifting of Father’s
excommunication was executed by Fr. Richard Shmaruk, a priest of the Boston Archdiocese, on
behalf of Bishop Bernard Flanagan of Worcester. While visiting Boston about ten years ago, I
spoke with Fr. Shmaruk and he personally corroborated the events that led to him reconciling Fr.
Feeney with the Church.
On pages 259 to 262 of his book They Fought the Good Fight, Brother Thomas Mary Sennott
diligently chronicles the reconciliation of Fr. Feeney, as well as the subsequent reconciliation of
several of Father’s spiritual descendants. Brother Sennott quotes from two respectable Catholic
news sources (The Advocate and the Catholic Free Press). I have independently confirmed the
quotations and context of the primary sources.
Brother Sennottt also notes that Father’s memorial mass was celebrated by Bishop Bernard
Flanagan in the Cathedral of St. Paul, Worcester. This would have given rise to scandal had
Father not been fully reconciled with the Church. Br. Sennott’s book received an imprimi potest
from Bishop Timothy Harrington of the Diocese of Worcester, meaning the book is free from
doctrinal or moral error.** Thus unless one is willing to declare oneself sedevacantist or
sedeprivationist, the evidence is overwhelming that Fr. Feeney died in full communion with the
Church without recanting his position.**”
catholicism.org/downloads/Peter_Vere_SBC.pdf