I think he meant trillions of monkeys, which would necessitate considerable volume for not just the monkeys work space and equipment (keyboards, monitors, power generation etcetera) but also their life-support systems (sleeping areas, transport infrastructure, waste-disposal, healthcare, recreation, atmospherics etcetera) and support staff (vets, tech-support, general zoo-keeping personnel etcetera). Probably need at least one fully developed planet as an industrial base for keyboard production alone to be fair.
Also this whole crazy setup would require the kind of total energy source only encapsulating a star could provide. Trillions is infinitishness on the cheap so it makes sense really. Economic.