I liked that arc. It kept pulling interesting twists and turns out along the way up until the final exchange. (Actually, my money was on Ryuu being naturally impotent, and having been giving Joe the 'fair shot'. Ryuu's already mentioned, possibly as a joke, that his own little swim team isn't that great. But then there's the question of whether Joe's just lying to do his part ensuring the child's future.)
Then that gets topped with a Dragonball joke.
As far as all the other comments about Ryuu and Joe... well, I think at the point Ryuu came into the equation in the first place, if hadn't existed, there would be just as many complaints about hot delinquents/part-timers who are OBVIOUSLY no good for the girls they're with, had seized another target. This managed to ride the center of the line, and everybody come out the other side seeming like a person with their heart in the right place, even if not everyone is a good fit for each other.