Carmack seems arrogant[1]. Which is why I take that statement as high praise.

It’s also a nod to his own fame.

[1] This is based on Masters of Doom. And the anecdotes are probably from the 90’s. And being arrogant does not mean that being confident in one’s ability is unjustified or that they are in fact not skilled. Being arrogant and being highly skilled are completely orthogonal.