There's been some talk about using Tulle or organza or some type of netting over fragile fabric. This YouTube video would explain what I am talking about.
https://www.youtube.com/watch?v=5gxv2dyRQAE
I wouldn't tie the quilt. IMO, that would put extra stress on the older fabric when moving the quilt around. Using the fine tulle over the original fabric and then machine quilting would seem to be the way to save the quilt top and allow use for years to come.