He was a postulant and not even a novice. The whole point of the offer was to give them a monastic formation, this offer was made to the entire community by the Benedictine priest who did the funeral. There was no brother anything as none took vows, all were some varied form of postulant/novice.
So postulants voted another postulant as superior? They did this after being given a chance at formation and then gave themselves vows?
There's more but that should suffice.
They're not benedictines. They may have non Benedictine vows though