That quote is not very convincing to me. Both parts of it are questionable.

Just being able to play chess is not a very high bar at all. Most 6-year-olds can learn it in an hour. Are the Chess hustlers at Washington Square Park all Gentlemen?

I don't see being able to play Chess well as any kind of deficiency. It could be that it's just someone's hobby. It doesn't have to mean they spiraled into madness, Bobby Fisher style.

(I can play chess, but not well, so I personally don't care about either half of that quote as it applies to me)