The Scott who posts at slatestarcodex.com is the Scott who is scott@slatestarcodex.com.
Therefore, the material Scott when attempting to pin down Scott in the context of slatestarcodex is scott@slatestarcodex.com.
Human X out in meat space could or could not be Scott, but that much is immaterial, as scott@slatestarcodex.com has been shown to be directly linked to Scott Alexander the blogger as a means of contacting him.
Thus I ask: what better proof could one have that scott@slatestarcodex.com is Scott Alexander, author of slatestarcodex?