Except that doesn't seem to be what he is proposing - you don't have a coop to assign labor, you have a coop to control wealth to provide livelihood. The membership does whatever it wants, the coop will, if necessary, pay people to farm its land or manufacture its textiles, but the cornerstone of UBI is that as automation advances the amount of human labor required for any of those constituent parts of livelihood will continue to approach zero, and when it does, you now have an apparatus of the means of production that provides for all your members needs.