The topmost line ends the hexagram in the water. Legge's translation describes wading through a stream until the water passes over the head, gives evil, and then adds that there is no ground for blame. Those two statements are not in tension. The outcome is bad and the conduct is not faulted, a distinction the text is willing to draw and most readers are not. In a hexagram about weight carried past what a structure can bear, this is the moment the crossing is attempted regardless.
The stroke is yielding in an even place at the top of the upper trigram Dui, correct by the ordinary rule, and it is the second of the two soft ends that give the ridgepole its weakness. The Great Symbolism reads the figure as a marsh risen over the trees standing in it, and the topmost line is where a reader is put under that water rather than left looking at it. The same Symbolism describes standing alone without fear and withdrawing from the world without regret, and this is the line where the first of those has consequences.
What the text withholds is condemnation, not the loss. Somebody who wades in knowing the depth, because whatever waits on the far bank is worth it, is not being called foolish. Great Preponderance opened with mats laid under a heavy load and closes with a person out of their depth, and the two lines together mark the range the hexagram covers: what careful preparation can hold, and what it cannot.