They cite the Christian believe in the sanctity of life of embryos as the source of the morals they don't feel obligated to follow. I don't think that is the main issue people have with genetic engineering, though. What makes people uncomfortable seems to be the homogenization of the population, and an enormous advantage for children born to parents wealthy enough to make their children super-humans through genetic engineering. I don't know if Confucianism has anything to say on that, but it seems pretty wrong by any ethical standard I can think of.
I wonder if there would be as many Chinese scientists bending their ethics if there wasn't an enormous financial incentive to publish high-profile findings.