Matrimony and reconciliation require the priest to have faculties. Since the SSPX has validly ordained priests but not the faculties (their bishops were illicitly consecrated), they were simply given the faculties during the Year of Mercy. This was done for the spiritual good of souls, NOT as a declaration that the SSPX is in good standing with the Church (because they ARE schismatic).
This does not mean the SSPX really should be celebrating the sacraments expect in extraordinary situations (such as when someone is in danger of death; in that case, the spiritual good of souls is always more important). The SSPX priests are under suspension a divinis, and really should not be celebrating the sacraments until they regularize their canonical status and return to full communion with the Church.