@GasperyJacquesRoberts If I'm stood at the top of a high waterfall and someone falls in to the river, should I be prosecuted if I don't jump in to try to save them? Does it make a difference if the person in the water is my girlfriend and I suggested we go there? I don't know. It's a difficult ethical question.
That isn't equivalent.
In this case, Plamberger suggested the climb, was far more experienced, didn't refuse to go when Kerstin had unsuitable equipment, apparently didn't know she had a bivy sack (so hadn't prepared for emergencies), went on the climb despite starting out late, continued on the climb despite the weather turning nasty, waved off a helicopter, told an alpine officer they were fine at a point when they urgently needed help, and then left her behind in an exposed, uncovered, vulnerable position, not calling for help until an hour and a half later.
There were many, many points that he, as the more experienced of the two, should have said, 'this is unsafe, I'm not going/I'm turning back', but he didn't. We don't know whether he pressured her to go on, or was angry with her and abandoned her like he did his ex-girlfriend, but whatever happened, he had multiple clear opportunities to prevent her death and didn't take any of them.