I’m afraid you are getting carried away.
Hashem knows that you will Daven and He knows what will actually happen. This has absolutely nothing to do with Moshe Rabbeinu looking into the fellow’s future generations. Do you think he saw people munching on pizza? He looked with Ruach Hakodesh into the person’s future.
A person, like a tree, has fruits. With Ruach Hakodesh, Moshe was able to look deeply into this man’s soul to see if he had any true spark within him; if any child from him down through the ages will ever convert.