If I remember right, person a buys a token from the store and places it on th AH to sell for in game gold. Im not even sure if you can redeem a token paid for with $ for game time, it might be limited to AH listing only.
Person B comes along and buys the token for gold, and then can only redeem it for game time/bnet balance.
So there’s no opportunity to flip a token for gold.
This may have changed over the years or I may be recalling wrong, I didn’t follow it too closely.