A neat gender balance would be better for the people involved than an insanely skewed gender balance that favours men.
That being said, one could substitute China -> America and, gender -> wealth, unmarried -> jobless, and I think the accusation would be similar. I've had Americans seriously tell me that the country is on the brink of civil war, which seems about as bad as anything that could come from China's gender imbalance. I'd link that to economic problems, it is the explanation that makes the most sense to me.
Basically, there is a real concern; but I'm not sure it is an /unacceptable/ outcome of the One Child Policy. It might just be an outcome. The OCP can easily be cast as a policy of courage and prudence; overpopulation carries a real threat of starvation and collapse if it overshoots what the local resources can support.