Grandparent meant that he did not see anyone else use Redstar as a main OS. So even though he could obtain it and use it, it was not a popular operating system

Grandparent meant that he did not see anyone else use Redstar as a main OS. So even though he could obtain it and use it, it was not a popular operating system in North Korea as a whole. Of course, perhaps Redstar is the de facto OS of workplaces or perhaps military operations.