"He is almost certainly a better overall programmer than I am." Hedging the claim with a lot of qualifiers. What's wrong with admitting someone is a better programmer? even giving someone else the benefit of the doubt?
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.