While it's true that they aren't going to report each other, it's safe to assume that if they engage in a sexual relationship sooner or later they'll mention that to some friend/coworker/relative, and since this is a korean series someone in a position of power attracted to noona will learn about the fact and use it to blackmail her into having sex with him.
So, while I absolutely understand noona's difficulties in holding back, for the sake of this series she'll have to endure a bit longer.