Rui's words were entirely serious; he thought that he would eventually conquer the entire Milky Way as a leader of human civilization. The reason that he thought was that they had paths, and the rest of the Milky Way didn't. Paths were a huge advantage that the other races in the Milky Way didn't have, clearly. And they allowed Gaian Civilization to defeat an army armed with much greater technology than Gaian Civilization could ever hope to have.
However, the reason that he was especially confident was that GAian Civilization had him. He was the ultimate leader, even if he was putting it mildly. He knew that they would have a much greater chance of success in conquering the Milky Way if he were the leader of human civilization. After all, if push came to shove, his power as a Martial Transcendent, and more importantly, his power to remain even after intervening into the information dimension, was the advantage that he had that surely no other entity had.
