> What he said wa that in his class what was important was syntactical structure. He probably felt that he didn't need to add that being able to construct a sentence correctly is a futile skill if you have nothing worthwhile to say.

Nonsense. What he actually says is clear and emphatic:
Content is a lure and a delusion, and it should be banished from the classroom. Form is the way.
He doesn’t say “my classroom” but “the classroom” in general.

Your assertion of what he may or may not think has no grounding in what he actually wrote. You may be right – but if so, he has let his claims run away with his mouth, which is not a great advert for his passion for the “clean English sentences” which he implies will automatically render thought equally pure and clean. I think insel’s got it right – it’s the faculties of analysis which are falling short: basically, he’s tackling an effect, and not, as he fondly believes, a primary cause.

Of course, the study of any discipline in a structured and analytical framework will improve cognitive faculties. I agree with you that his approach has validity, as I said above – just not the exclusive validity he claims for it.

He notes that “once ideas or themes are allowed in, the focus is shifted from the forms that make the organization of content possible to this or that piece of content, usually some recycled set of pros and cons about abortion, assisted suicide, affirmative action, welfare reform, the death penalty, free speech and so forth. At that moment, the task of understanding and mastering linguistic forms will have been replaced by the dubious pleasure of reproducing the well-worn and terminally dull arguments one hears or sees on every radio and TV talk show.” One can understand his frustration at having to drag his mighty intellect down to the level of his mere students, but he misses a point clear to many other teachers: a variety of teaching styles is required in order to reach all pupils. One of the keys to this is to build on their existing foundations of knowledge in order to gain their motivation: many students will respond more effectively to a lesson of grammar, for example, if it is embedded in getting them to communicate more effectively on a subject they care about. His students are apparently not like this – I will take that on trust despite the evidence in most classrooms to the contrary, but I do not accept that his techniques will work universally. Many dull pedants have been turned out by these pedagogic methods in previous years; knowledge of clear structures does not a writer make.