Since what we hear in the newspapers is probably only 50% of the whole story - I will feel free to wildly speculate....
The woman was a Pro, and when she learned who the guy was, thought that a big pay-off was possible. Or, she was a Pro, and knowing DSK’s predilections, one of his many political enemies sent her, hoping DSK would take the bait and leave a bit of DNA.....
1st clue....She volunteered to work on that particular floor.
I believe there is another employee involved.
Don’t have a great deal of sympathy for either party here. They both deserve what they get.