Legal issues aside as thats already been covered (and there aren't any) the issues here to me seem to be ethical one's.
I personally woud use the photo's on the grounds that when our girls join us they take on a whole new persona.
I look at pics of Kate when she was Snaggles Audrey and she is not now the same girl.
Same with Tiffany when she was another members Abbie (actually, the difference in appearance there is quite dramatic despite her hair being the only physical change).
They are not the same girls and that goes both ways from both the seller and buyers perspective.
The questions to ask yourself are:
1) Does her new boyfreind still refer to her by her old name... No? different girl. Use the photo's.
2) Does her new boyfreind treat her as his girlfriend or a sex doll... If a Sex doll, then treat it that she's ceased to exist as her old self and use the photo's (and we'll all arrange a rescue operation for her!).
As a caveat though, even if the buyer does not respond it would be a polite gesture to tell them that you are going to be posting some old pics, that are tasteful images, under her old name, with no reference to her new persona. A response however is not required as you have informed them of what you are going to do and the message was simply a courtesy to a fellow site member.
I think that Tommo's excellent three rules like Asimovs rules of robotics are a sound ethical basis to work to.
And on final override, As Flash so excellently put it (paraphrased). Your pictures, the images of who she was, keep her alive. (profound Flash
)