Do you think delivery workers could fetch the food from thin air like witches and wizards in Harry Potter movies and books? There are cooks, food factory workers and shop assistants processing them. And there also are workers working in factories supplying electricity, water, medical material and equipment...etc. “Essential workers” and what level of quarantine measures are supposed to be taken are defined by the authority which rules China, not by military fan boys and girls who rule a internet forum. In 2020, thousands of Chinese soldiers involved in a hand-to-hand combat with Indian soldiers. If all these soldiers had been quarantined for that, Indian troops would have already taken over Lhasa since no Chinese troops left to guard the border.
It is just like what I said in my last post: if the time of launch mattered most to Chinese authorities, they would allow workers returning work. But I don't think they except the shipyard manager care it that much.