well, in the authors statement he hasn't told anyone, but he did say to speculate.
we know that the friend is coming into town
we know that the friend is ... fond of sex and comfortable with her sexuality i guess is the best way to put it as she's pushing vi to get laid, and just other context from the phone conversation... the fact that the skirt is at the "can it get any shorter" length would indicate that the person in the image fits that profile
and if you look at the bottom left of the image, you can see what is probably a suitcase.
So, it is a statement.
But it is also a guess.