For me, it's not so much the "cosmic Christ" as the idea that Matthew's magi come to worship "that."  They didn't.  I might have a problem with the author's version of "cosmic Christ" or not, but it's unclear what she means.  Like the Mormon "Godhead," a shared vocabulary doesn't imply shared meaning.
As for the theology, I would say, "Who can tell?"  I find the article so poorly written that any meaning has to be supplied by the reader (a verbal-Rorschach) versus whatever the author might have meant, if anything, in the writing.