What's next----Fellay offering to cover for the pope during papal vacations????? I don't think B-XVI would agree.
"Aren't those who are excommunicated unable to obtain spiritual benefits for others???? At least so long as they are excommunicated?"
No laymen who attend SSPX chapels have been declared to be excommunicated nor schismatic, at least by the Church. The Ecclesia Dei Commission has confirmed on numerous occasions that a Catholic can fulfill his Sunday obligation at SSPX chapels. The vast majority of those 1 million rosaries are from the traditionalist laymen.