Well, firstly, it isn't. There are higher Geekbench 6 CPU scores, even forgetting the ones that appear to be fake or at least broken. But secondly, that would absolutely not indicate that it is the "fastest single-core performer in consumer computing". That would indicate that it is the highest scoring Geekbench 6 CPU in consumer computing. Whether or not that's actually a good proxy for the former statement is up to…
SPEC has been the industry standard benchmark for comparing the performance of systems using different instruction sets for decades now. Traditionally, Anandtech would have been the first media outlet to publish the single core and multicore integer and floating point SPEC test results for a new architecture, but hopefully some trusted outlet will take up the burden. For instance, Anandtech's Zen 5 laptop SKU results…
The only good comparison is to judge a variety of real world programs compiled for each architecture, and run them.