He trusts Nick more for the fact that Jordan is a powerful women in this story but it's because she lies example when she borrowed someones car and it rained while the roof was down and she lied about it. Nick and Gatsby start to grow a little bit of a bond could help that. Also at the first party he notices that Jordan and Nick are at the party together. It also could be the fact that Nick is her cousin. Another thing could be that this time period women weren't really a huge part of the society...men thought they were better so he could have asked nick to do it for the fact that he was a man.
