Can. 1335 ...If a latae sententiae censure has not been declared, the prohibition is also suspended whenever a member of the faithful requests a sacrament or sacramental or an act of governance; a person is permitted to request this for any just cause.
Isn't it also the case that a priest must "unite himself to the intention and charity of Christ" in order for sacraments to be valid? Having encountered priests with faculties whose words and actions make it impossible to have moral certitude that their intentions align with those of the Church, it seems apparent that the situation is not as black and white as some perceive it to be. The intention of the penitent is also a consideration, as well as the prudential judgments necessitated by particular situations (such as, for instance, when a bishop fails to provide trustworthy, accessible confessors with faculties). Can. 1335 seems to cover such exigencies.
I'm not sure where SSPX would be providing such confessors that there aren't other alternatives, maybe you could clear that up a bit.