This is 9 years ago. So I think it was merely an advertisement for the girls as available to the elite in South Korea. Girls Day came from a small company. Dream Entertainment. So advertising the girls, for the company, who could use them to maybe get more favorable coverage or promotional deals is the goal.
Because really, the other companies are doing it. Even Male idols have anonymously said that wives of CEO's sometimes offer them money and gifts and say they are fans. And then later call and ask them to stay over the night while their husband is away because they are lonely. And if the boys say "no, you are married", they tell them "I helped you so much, can't you just stay with me for one night? Is this what you do after I helped you out?"
This may also lead into the wife having pull with her CEO husband and recommending his group.