Even if they claimed that, it seems highly doubtful based on their results here. There is nothing in the specs that suggests that the gap in performance on a multiplat should be in favor of the PS5, the latest stats have the Series X beating the PS5 in just about every on-paper metric, CPU speed, RAM speed, bus width, pixels per second, texels per second, triangles per second, rays per second. At the very least Series X and PS5 should have near identical performance. The only thing that can explain a performance gap like we're seeing on these launch games is simply bad optimization on Series X, and the best explanation for poor optimization, on games like AC and Dirt 5, which Microsoft had the marketing rights on, is that dev kits and dev tools released too late for developers to optimize properly ahead of release.
Yes it's still early in the console generation, on specs it seems like xbox should atleast be on par if not slightly better. However ps5 has the ssd advantage, has unified ram but not split, and supposedly better i/o system. if ps5 does indeed have the better i/o, then it may over come the cu count advantage/teraflop of the series x.