Hardly. First, it's not really a metaphor, more of an analogy; it could be reworded as:
My brain is to Carlsen's as Carlsen's is to the best computer's.
It's pretty obvious he isn't talking about his brain qua a biological organ. He's referring specifically to chess skills.
In that regard, the best computer chess engine in the world absolutely dominates the best humans. Even with a pawn or two removed as handicap, the best humans struggle to get draws.
There was a recent match played between the world #5 human (Nakamura) and the world #1 computer (Stockfish). Even when Stockfish played black, used a handicap of removing the b-pawn before beginning, and didn't use any opening books, Nakamura was still beaten.
The age of Human vs. Computer competition ended pretty conclusively in the mid 2000s, and the gulf has just widened.
