I hope you read the entired article, because you just took this part out of content. He stated that it is one of the ways to establish deep ketosis FAST; it is not consider blood glucose of 60 is not HYPO, but on the low side of the current FBG range: 60-100. I was hitting mid 50s while taking metformin without even noticing, and feel normal with BGs 60 too. For a non-diabetic person is not a problem to hit low BGs fast when carbs are restricted and glucogen stores are depleted especially if one is athlet and does weight training.
Lyle McDonald is very well known and respected author of many books and articles, guru of weight loss/nutrition, exercise, and he goes into explaining human biochemistry into a great level of details never mentioned in popular diet books written by some doctors He wrote "The Ketogenic Diet: A Complete Guide for the Dieter and the Practitioner" which is considered to be the most comprehensive book on low-carbohydrate diets ever written...