What construct is Murray asking you to reconsider?

Murray is asking us to take another look at all writing and to see that no matter what the piece is about it is autobiographical. he wants us to see that because everyone is different and has a different "thinking style" and "voice" that this turns their writing (no matter the topic) into autobiographical writing. if someone else had written the paper in their own voice or style it would be completely different and only reflect the writer.

How might we apply his ideas to the kinds of writing we find on Wikipedia, or any encyclopedia?

Each of the articles has a different author. this means that each article is an individual's autobiography. each article is written in a different voice and reflects a different style. although when you read the articles they all seem to be written by one person, if you look closely you can see tiny bits of personal opinions and life stories.