Is man the center? Not independently, not ultimately, and not ontologically.
But in the economy of God’s covenantal dealings, man is (a) created as God's image-bearer to whom and in whom God reveals himself, (b) the focus of divine redemption, (c) the assumed nature in the incarnation, (d) the dwelling place of the Spirit of God, and (e) the bride of Christ in glory. So, although man is not the ontological or metaphysical center of the universe, he is functionally and redemptively central in the divine plan. In that sense—and only in that sense—one could argue that man is the center of the universe.
The original claim—"man is never the center of the universe"—is ultimately true when measured against God's intrinsic supremacy and theocentric teleology. But a counter-argument can be sustained within the framework of God's covenantal economy, namely, God made man central to his redemptive and incarnational purposes. And that is likewise a form of centering—albeit always derivative, dependent, and for God's glory.
There is certainly a Christological argument for the conclusion that man is (at least in some carefully nuanced sense) the center of the universe: The Son of God became man, which is the most radical centering of humanity in all of reality. He did not assume angelic or some animal nature. Not only that but this humanity isn't a temporary cloak but now and forever hypostatically united to the divine nature. In Christ, manhood is joined to Godhead, the glorified Christ reigning bodily from heaven, whose human nature participates in the eternal rule of the cosmos. That which was dust is now seated at the right hand of majesty. That reaches beyond inclusion to exaltation.
"For surely it is not angels that he helps, but he helps the offspring of Abraham. Therefore he had to be made like his brothers in every respect, ..." (Heb 2:16-17).