Expressing romantic interest in a co-worker or classmate is not de-facto inappropriate. Your advice is solid for folks in positions of power, but for the rest of us, not so much. The idea that young men and women who work together should be forbidden from exploring relationships with with classmates or coworkers is a kind of bizarre neo-puritanism. (Your human nature? That's bad! Ignore it!) And for what? To prevent the occasional, momentary discomfort of rebuffing a respectful advance?
Of course nobody should have to endure sexual harassment, socially inept creepiness, or blind persistence from unwanted suiters. And people who engage in these behaviors should be paid a visit from HR (and eventually receive a pink slip). But the vast majority of adults are capable of tactful communication, and should not be prevented from exploring the full possibilities of their interpersonal relationships simply because the relationship began at work.