Stanley Fish argues that composition classes need to teach only writing, not subject matter. It's odd that Fish understands the danger of a narrow-minded approach to defining the teaching of literature (his primary field) and then demands a narrow-minded approach to defining the teaching of writing. All writing is about something; good writing doesn't come from diagramming sentences and learning what a gerund is. Good writing requires a subject matter, and that's why writing in the disciplines and similar ideas are valuable.
Now, it's possible that some teachers focus too much on the subject matter and too little on improving the writing about it. If so (and we have no evidence of it, certainly not from the ACTA report), then we should encourage greater focus on writing, not ban subject matter from writing classes.
As I've noted in my books, especially The Myth of Political Correctness (which Fish was responsible for having published by Duke University Press), one of the major attacks on academic freedom comes from right-wingers who think politics should be banned in composition classes. Sadly, Fish is giving ammunition to this attack on academic freedom simply because he shares their old-fashioned opposition to the new trends in composition.
I happen to think that Fish's approach to teaching composition sounds boring and stupid (without taking the class, however, I can't really judge it for myself). However, it seems to work for some students, and I have no doubt of his abilities.
We need a pluralistic approach to writing, as we have to other fields, allowing teachers the freedom to experiment with different ways of teaching composition. And we need better ways to advertise the differences in classes, so that students with certain weaknesses can choose the best kind of composition classes. Perhaps the best approach is to have campus-wide writing contests, where students in composition classes can have their writing graded and the best students (and the best teachers) can be recognized and rewarded for their work and then encourage to train other teachers in their techniques.