The argument seems confused.
'Few developers admit that they do only random or partial testing and many will tell you that they do complete testing for some assumed vision of complete. Such visions include notions such as: "Every line of code has been reached," which, from the perspective of theory of computation, is pure nonsense in terms of knowing whether the code does what it should.'
It is as if he had never heard of 'use cases', which in fact are not mentioned anywhere in the text - a pretty glaring omission. The portion of the code that is reached is irrelevant as long as you have covered all of the use cases of the system. Ideally code that is not run for any of the use cases should be removed but it does not prevent the software from being fit for purpose.