You’re trying to make a sort of hybrid between moral laws and free market economics. The author makes a living by people buying his books, but if no one is buying his books then there’s nothing immoral about that. It just means that he’s going to need to find something better to write about, or to be perfectly frank he’s going to need another job.
People don’t have the right (moral or otherwise) to their preference of work. I’ll use myself as an example. I’m an environmental engineering student and my preference would be to work in the environmental field. So far I worked last year as a materials tester and this year in water management and quantity monitoring. Which is close, but I’d like to get into more environmental stuff (remediation, cleanups, quality monitoring, that sort of thing). I don’t have the right to work in that field though; I’ll need to get hired by someone and make due in the meantime. There’s nothing immoral about that, it’s just life.
