I think it's fine...it's art and shows nothing inherently wrong.

The noose doesn't inherently mean the picture was irresponsibly taken. For all we know, it was held up by velcro at the top. We see people shot, blown up, stabbed, and mutilated every day on public television...this level of implied/potential violence is...tame.

Beyond that, even assuming all the ties and binds are 'real,' it comes down to consenting adults. One hopes the girl understands the risks and acts accordingly, but that is part of being an adult and being free.