Bruce had no contacts that were capable of resolving the trouble that Windsor family was facing. Instead he knew of a business oriented family that would be willing to do anything in the name of Zach. After all, Elizabeth family had almost become in-laws with his Luther family since Zach was already a part of his family by then. Even during their escape from Elizabeth city, the family had helped them out until the end.
Despite not being on the same level as Windsor family, Bruce believed that Elizabeth family would have some means to help out with the situation. They might be lacking in terms of capital but the Elizabeth family he knew of was more than capable of standing toe to toe with the top families of Byzantium city if they ever got the chance and the same amount of capital that the four families enjoyed. Therefore, he felt that asking the Elizabeth family for help was only the right thing to do.