 He thinks if you don't put your shoulder into things, then you don't really mean it. Secondly, if he's not willing to do the job of setting up the shop before the employees get there, how can he expect them to do that when it's their days to open? He chose to do it on this weekend because it's a family weekend. He has a family too, but his employees don't have the luxury of choosing their own days off, so he's given them this day so that they can spend time with their families.