What I don't really get here is why the party machine would go to great lengths to protect a vice premier - he must still have pull. I can believe that the regime would want to minimise embarrassment or any implication of fallibility - do they only arrest former officials when its politically convenient?
Two main reasons.
Firstly,the propaganda machine's No.1 priroty, is to protect the Party's divine image: it is pure and determined, it is destined to lead our people forever and ever. The higher a person in the party's bureaucrat ladders, the more untouchable they become. If the party leader was to punish someone with high status in the party, he would done it in the name of "anti corruption", so he could punish his enemy and made himself looked good at the same time. Sometimes bureaucrats even get reward after they fuck up something, because they take one for the team.
Whether Zhao Gaoli is a close associate to Winne the pooh or not (it's hard to confirm), this is not a determiting factor in this case. At least for now, a vice premier is too high to "sacrifice". Cause you know, so many important people in the party are offenders, they don't want to set a precedent. The party's image must be protected.
Another reason is China today is a highly Patriarchal society. Proganda department have openly declared feminism is "corrupted western value" and it is very, very hard for abused woman voicing their condition. Recent years there were many infamous sexual assaulted cases in China that sadly haven't got that much notice outside of China. Usually, those victims were openly silenced, mocked, harassed, then lost the case(if they could took it to court in the first place).
But,there was ONE cases,that the party quickly arrested and punished a rich sexual abuser. That abuser is Kris Wu, a very famous singer and idol in China. The party took this case as evidence that they cared about women very much, publicized it, and tried to gain support from Chinese women.
But guess what? This Kris Wu guy, is actually Chinese Canadian. He had zero political power.
en.wikipedia.org
So, the party arrested him very willingly. Yes he deserved it, he is a creep, but you can easily see through the party's principles.