Thunder Child, your posts seem to be unnecessarily confrontational and petulant.
Even though Alex is a competitor (directly, as I also teach General Navigation) I would say he is extremely competent, knowledgeable, approachable and helpful . Your comments about him are not justified by his posts in any way.
Alex's replies here have been reasonable, and he has corrected the answer to his question. We all end up with errors in our teaching material. You ask a professional editor about this sort of work, you will find that however much proof reading is used errors remain (I did talk about this with a professional editor).
As you can see from this thread the INS questions can have complex answers that are not always clear-cut. I generally don't teach INS (though I have), our instrument specialist does. His other job is as a 757/767 training First Officer. He still comes across questions to which he does not know a definitive answer as they are type-specific. That seems to be part of the confusion over this question, and is a common complaint about JAA questions. We have to second guess what the examiner means!