It's insane, isn't it? Why do so many companies act like employees are their indentured servants and not professionals who provide their services to them in exchange for money?
If anything, the boss should have said "Are you sure just 3 days are enough? How about you take the whole week off instead and come back fully refreshed?". I do hope the court throws the book at them - time off should be a goddamned sacred right if every employee.