Well, for one thing we do our volunteer work for the glory of God, not for Fr. Rostand or Bishop Fellay.
Who benefits by our efforts? We render honor to God, and even our fellow parishioners aren't benefiting personally, but they are better able to worship God on their part -- so it's still for God ultimately.
I suppose it could be argued that having a beautiful/flower-decorated altar, a chapel with paid bills, clean floors, resonant choir, or hot coffee in the hall will encourage people to attend the SSPX chapel.
Can we protest to the human members of the Society without being prejudicial to our duties to God or to souls? In other words, let's not withhold any honor or glory to God by our "strikes" or "protests".
If funny business starts happening at SSPX chapels, then by all means leave completely. But we should be wary of depriving ourselves of the life-giving sacraments of the Church. It must be for a grave reason -- like Novus Ordo grave.
I don't think "a weasel of a priest" is enough of a reason.