Maybe I wasn't very clear. By going to a Resistance seminary you are going to become a vagus priest, unless you join the Dominicans at Avrillé, which has a structure. Some from Mgr Faure's seminary have joined Avrillé. There is a very good school at Avrillé and almost all the boys consider at least at some stage, whether or not they have a vocation. The option of becoming a vagus priest or staying at Avrillé is the options that they see. And these two paths are not appealing to all.
I'm thinking about the next generation of priests not this one.
If old-school SSPX (today it would be called "Resistance", "SAJM", etc) is considered "vagus" then there is absolutely nothing wrong with being a vagus priest.
Because we are not living in normal times. Jurisdiction (authority) comes in second after the Faith itself. That is the founding principle of the Traditional Movement.
If a priest being part of a structure (but still without any actual "jurisdiction" or authority flowing down from the Pope) is the same as absolute vagus (being an independent priest, his own boss, a law unto himself) then I guess we're stuck with vagus priests as the ONLY option for a good priest, during this Crisis in the Church.