Regardless of what anyone says. The weaklink set the pilot up for that or could have. (maybe the rope broke or the release let go.) My weaklinks would never put me into a hammerhead stall like that.
A two "G" might just be enough to cause this. The pilot was climbing way too fast.
A weaklink will protect me from a tow operator like the one on the other end of the line shown in this video.
If I conduct every second of every tow flight as though the tow vehicle could fail, the rope could break, the release acts prematurely, the tow driver releases that end, ---that is all I will ever need.