It's a nice parallel - I like that it could be both a compliment and an insult.
He was relevant at the top level of the game for a short period of time but only in one fairly obscure format?
He reached #2 on the active rating list and #5 on the all-time rating list in classical chess. Do you consider classical chess to be a "fairly obscure" format?
The things I said are true of the poker player Doug Polk. Doug Polk was one of the best 2-player Texas Hold'em poker players on the internet for a couple of years, but only at a point in time where the format was pretty dead. I know very little about Hikaru Nakamura, but it sounds like Hikaru is a much greater chess player than Doug is a poker player. Which is fine, I guess the similarities lie elsewhere.