> How much time did he spend on coding as Linux got bigger?

Yeah, I don't know. But even just keeping up with PRs seems quite time intense.

> And you could argue PR reviews was how Linus performed his management function

You certainly can, but just because the word "management" appears in there, it is wholly different from the "management" that the original post is talking about. But yeah, you can call both management. You can also call a software developer a manager of the codebase I suppose.