So if I understand correctly, Dave, you would accept something from someone's private tree and then publish it on your own public tree? I know in this case you will argue that it is a public document, but would you also do the same with any other information you were given from a private tree ie photos, family stories? This is the very reason that so many of us keep our trees private. If I share photos I always ask that they are kept private and are not added to a public tree. I hope that the person I am sharing with will have the decency to respect my wishes.
To go back to the point about being ignored - has the person in question responded at all? If not, how do you know that she has seen your requests? She may not be working on her tree at the moment and so is not using Ancestry, she may be ill or have even died. A good friend of mine, the mother on law of a second cousin, has 4 private trees on Ancestry, all highly sourced. However, she sadly died two years ago. As the trees remain there for all to see, anyone asking for details will not get a reply.