Keitaro was probably making sweeping generalizations based on his local experience
and he's right in that the Japanese took an idea for "noodles" from China and "re-invented" the idea as Ramen.... which the Chinese are no doubt re-absorbing and then transmogrifying it yet again.
I will say, finding "ramen" in a chinese restaurant is kind of like finding "hot dogs" and "french fries" in a Vietnamese restaurant ... its a concession to the occasional customer who ought to be smacked about the head for not trying new things
Actually, its a bit more like finding kimchi in a "japanese" dish restaurant I guess.
The advent of cross-cultural contamination also is making it even more difficult to say some dish is of culture "X" or "Y" .... kind of like saying pasta is actually Chinese and the Italians just borrowed the idea.