I do agree it is preferable to have the schismatics return one at a time. It is clear Fellay and the lefevbre cult have no intention of ending their war against the Church Jesus established. They are quite mad in thinking this Pope will invite them back en masse so they can wage war inside the Body of Christ.
Were I Pope, there is no way I'd approve use of the old liturgy for those who thought the normative mass evil because such an idea suggests more serious problems with the Living Magisterium and its protection by the Holy Spirit