[kelnos]

The idea the author is talking about is explicitly not the "I am..." stuff. The "I consider myself to be..." stuff is what is important to his thesis that the "descriptors you hold dear to your self-image" (which he calls "identity", but I agree that can be an ambiguous term) can blind you to opinions and evidence contrary to what you already believe, and make it difficult (if not impossible) to have honest conversations about things.

I may literally be an average-height, average-build, bald, white man, but I don't consider any of those things to define me; they are not central to my self-image (at least I don't think they are; it's possible I've let some of that creep into my psyche more than I'd like). Yes, they are literally a part of my "identity", but not in the way that is relevant to anything the author is talking about.