2013 Gender ratio in China: 1-14 years of age: 117 men for every 100 women. 15-24 years of age: 111 men for every 100 women (CIA)
In all cultures, it is men - young men, young unmarried men in groups - who are given to violence.
China doesn't fear shengnv. It fears leftover young men acting in concert against social injustice.
'Older' unmarried women are stigmatized so that young women will choose to marry early and sacrifice their careers to social stability.