Nobody does that stuff alone. I think a more accurate description would be that he seems to be a force multiplier for the team he leads, which can have a bigger impact than any singular engineering feat.
If there are only a handful of people capable of doing this or even just one then 10x or 10000x doesn't make sense because that is a productivity metric. 10000 normal engineers wouldn't be able to do it just like 10 juniors can't do the job of one senior.
IMHO, the correct way to look at it is to compare impact/results.
A 10x engineer might not get 10x done, but their work will be 10x better in a combination of ways: quality, maintainability, speed, portability, extendability, etc. Hopefully the ways in which their work is better fits the priorities of the organization.
That’s the only way you can really call someone an N-xer compared to a productive individual contributor.
Someone like Jim Keller is a big multiplier at a higher level. People today understand the value an executive like Steve Jobs brings, but usually there’s debate on the value before it becomes clear a few years later.
