This is because of the market, but I strongly believe that if the project is good enough, the team should not be scared of listing
Not just that particular project you are referring, but many devs are being scared of this down fall market and most of them are delaying listing their coin/token into exchanges. This is basically due to they do not want their coin/token to get dumped due to the condition of this crypto space. I think this must be a good action as delaying for some time before market will be restored into positive trend, may ensure that their coin will not be wildly dumped so that they will not let their project to go down.
Due to the increase in fraud, the ICO market is fading, and I think the main reason why these projects cannot be successfully listed is that they are just a scam.
This could be another reason for why some ICOs are delaying their exchange listing but OP has clearly stated that the project he is engaging is really good one and I believe he must have did all the needed due diligence.