This is certainly interesting research, but hardly unexpected. Strings in my experience easily evolve into knots, and don't easily untie themselves. This is all part of the second law of thermodynamics. It seems there are "downhill" bits of evolution, like loss of sight in cave-dwellers, or strings knotting themselves, and "uphill" bits that go against the second law and need the ratchet to stop them slipping back. I don't see how this helps with your theory of "designed evolution".