Vague "efforts to steer her daughter away from climbing" are the Greek-myth workaround. Surely Louise could have told her that she knew specifically that she would die on this trip, this date...
In the story, it is implied the ability to see the timeline all at once, non-sequentially, comes with the loss of free will. It's a different mindset where people think they are play-acting rather than choosing the future. Of course we find this puzzling -- after all, we think sequentially :P Louise didn't warn her daughter because it wasn't in the "script" of the future.
My point is that if she made a meaningful choice to make the phone call and find out the term "non-zero-sum", as manicdee was claiming, then surely by the same token she also made a meaningful choice not to warn her daughter.