Sammy
It seems to me like Chip is asking a very valid question. He did not say that the method was incorrect. He's seems to be simply asking the question to determine whether Newtson's pitching opinion is to use the hips or the arm swing to determine pitch location because Newtson's posted opinion is vague.
Also, I do not think it's fair to take it upon yourself to make it sound like Chip's pitching methodology is all about absolutes because I can tell you from first hand experience that it is just not the case. I'll give you an example:
My older daughter's pitching coach is Chip. My daughter's stride actually crosses the power line a bit so she has to slightly close her hips and come across her body. In other words, she's a RHP. When she pitches, she steps slightly towards a right hand hitter, then closes her hips slightly to throw a strike. Now....your post would assume that Chip would not stand for that because you assume he's a coach of absolutes. Nope! He studied her mechanics closely, came to the conclusion that she was not hurting herself in any way pitching like that, and let her continue. I actually questioned him about her style and the answer he gave me was "Hey, as long as she remains accurate throwing like that, she's actually concealing the ball a bit longer so it reduces the hitter's reaction time. Her armswing is fine and she has a good finish. I'd let her go with it. She's throwing good."
It seems, based on your own post, that Chip is indeed an accomplished pitching coach due to the fact that Chip let my daughter do her thing based on her ability, as well as some of his other students.
The majority of people on this forum do not have elite pitchers, they have dd's that need basic instruction. Directional striding to hit spots is a safe, solid, tried, and true method of coaching.
Len