While interesting, it's comparing 5000+ Tensor Processing Units against 64 CPU threads. I suspect this isn't a fair comparison by watts spent.
> Training proceeded [...] using 5,000 first-generation TPUs
> We evaluated the fully trained instances of AlphaZero against Stockfish, Elmo and the previous version of AlphaGo Zero [...]. AlphaZero and the previous AlphaGo Zero used a single machine with 4 TPUs.
So the 5000 TPUs processing power or energy consumption should be compared with those spent in devising Stockfish, not running it.