The listing is not about connecting, I feel, the fact that the information and codebase presented so far is not functional and bittrex will not be going against their policies of listing any coin for trading if it does not pass their rules, most especially after stating the risk involved, most especially this one below.
Bitcoin Gold codebase also contains a private premine of 8,000 blocks (100,000 BTG). Please be aware that if a market does open there is a possibility of the developers selling their premined BTG on the open market.
A lot of explanations from BTG crew I guess.