Don't have the game in front ofe at the moment but I believe that Gold is independent. It's not classed as a good. I'm sure this is specifically mentioned. It's important because one of the Targi tribes special powers is play one good less when using a future purchase action.
Gold is tighter than getting goods in this game and I think that's the designers intent.
Yes, I agree gold is not a good, as mentioned in the rules. I'm just not sure if and where it's been said that gold cards are removed from the game as they are used.