The point is, why would you specifically single out sex work? Why should the people "still be able to work a 40 hour job and pay for food and rent" without getting involved in sex work in particular? I.e. jobs with far less dignity, or far more danger (e.g. logging), less comfort, etc., are ok in that broad "work a 40 hour job" category, but sex work is not ok? You could as well say "some people find retail jobs degrading/exhausting/unfulfilling [many if not most retail workers do, I suspect], so they should still be able to work a 40 hour [non-retail] job and pay for food and rent".

The only real reason to single out OF (an objectively superior option to a median job, if you can get it) is precisely the puritanical morality.