Eh, I bet he’s using some normal Latin vocabulary and orthography skills too. I suspect he wouldn’t do quite at well memorizing a truly random set of combinations of 26 symbols.
You say that, but there are some world-class Scrabble players from Thailand who play Scrabble in English, a language with a completely different alphabet and orthography from their native tongue. They don't necessarily speak English well, either. One beat Nigel Richards for the World Championship in 2009 [0].
I think it would take Richards about 20 minutes to learn the Cyrillic alphabet and a few weeks to get familiar enough with the patterns of Russian to be a competitive player in that language. World champion is obviously a harder ask, but I wouldn't rule it out.
