These were exactly my thoughts when I first saw the critics of this book some time ago (btw I don't see much added value in this publication relative to what Alexey Guzey wrote initially).

Like I agree that removing the bar is bad, but Walker's takeaway is pretty much the same as that of the original paper from which the graph is taken - the paper states that predictor for injury is sleeping less than 8 hours, which Walker points out as well.