Wow, what a crying shame. I do have a helpful note tho I hope. Because it looks like the thread is up off the fabric you should be able to clip a thread and then 3 or 4 inches clip again and pull, it looks like it is loose enough that it will slip out. That is better than having to pick every stitch. I am sure your friend must feel terrible about this. I had this same thing happen to me with one of my quilt tops that I was quilting for myself. I was so frustrated but I did find it before I had done more than one row across. Now I check all the time to make sure it isn't happening. It took me along time to figure out what was wrong. Finally I called the distributor where I bought my machine. He had me to do one small physical adjust to a part on my machine that changed the thread path some and it corrected it immediately. What kind of machine did your friend use? It might need the same tweaking and I will gladly share how to fix it.
Thanks,
Sherryl
Candlequilter
By the way that is a beautiful quilt you have there- wonderful job on the piecing.