Here is the agency's response when asked why they did this:
Thank you for reaching out and we understand your concern. As per point of arrival we recommend to put New York or Los Angeles as more touristic destinations. When Liuba is going to have her visa interview with consular officer he/she will find it suspicious being that the person who have never been to the USA is going to Atlanta, but not NY, LA, SF, Miami, etc. They are very good psychologists and have a lot of experience to filter cases that doesn't have a direct tourist purpose. Therefore, we recommended to put NY. As far for the dates, it is also doesn't look good on the application that the Applicant is flying to the USA straight after the interview, in their mind the trip needs to be planned at least 3-6 months ahead, unless it is an emergency, and tourism is never an emergency.
Nevertheless, if Liuba gets approved, she can fly the USA straight from Bucharest to Atlanta with no problem. The Visa is going to be issued from the next date of interview and it will be valid.
As far as what to say at the airport: she can either say she had a convenient flight option from Bucharest and she is flying to NY in just couple of days and her plans changed, being that Russia has extended winter holidays she decided to use this option.