It was an unfortunate incident. But I will give the benefit of the doubt to the cops. Perhaps they were unaware that the lady had schizophrenia. What you are supposed to do, when someone charges at you armed with a baseball bat?
She was a 66 year old woman who was in limited shape.
The issue is that he would not have done that with a big guy. He would have taken out his sap or mace.
Many people who are attracted to weaker people, because they like overpowering them, become police officers. It is a connection that is very strong and historically true across cultures.
In the United States police are famous for a lopsided treatment of vulnerable people, especially women. Many police who would never think of using extreme force against a man unless absolutely necessary are quick to "show who's boss" to a person they know can be beat easily.
The vast majority of cases where police officers prey on women do not make the news, but people who have worked in various fields know that it is a severe problem. In this case the victim was a woman, a schizophrenic, elderly, frail etc so she was too attractive as a victim to the cop. His buddies have the same attitude but they know it's "all for one and one for all" or they will all fall. Like somebody famous said in the U.S. war against Britain, "We all hang together or we will each hang separately".
A secondary issue is the selective choice of which police officers are 'defensible' by the gang. A cop who plays the game will be defended at all costs against outsiders, no matter what he does. A cop who pokes fun at the fake macho culture will become a target. You can research the so called "nypd cannibal cop". His offense was making fun of the cops who pretend to be pillars of the community. A complex criminal charge was made against him that gave the appearance that he was a dangerous person hiding behind a badge. The truth is that he was only guilty of making fun of the real predators. Likewise, in this case, there will be threats against the judge, by police officers, to force the case the gang's way. There will be all sorts of crimes commited by police officers to try and help their buddy, and not a bit of it will make the news.
Now there are a lot of people with resources to monitor the police, so we'll see what happens.