They are not trained to deal with fragile people and the people there are not committing crimes! Paramedics have every type of resource and restraint we could need to safely manage the combative dementia patient and unless they were armed (God forbid in an Alzheimer's unit although some moron might argue for it) there is no need for police there.
The example given would be a very good example of police brutality - given the 91-year old was not brandishing a weapon and directed intent to injure the officer.
I was raised to respect law enforcement and managed to stay completely out of trouble. This does not overshadow the fact that my eyes are, also, wide open. Everything the majority of society sees upholds that respect. I don't think society, in general, would give a 5-star rating to a movie or series depicting the real and sad side of cops completely out of control.
However, all one has to do is open their eyes, their minds and be able to voice their concern over brutality.
Police brutality is growing and rising. From Eric Garner to Philando Castile, the epidemic of officers who shoot first and then think later is out of hand. Many innocent lives are destroyed, families ripped apart and people are brutalized all because of panic and in some cases, the insatiable urge to kill. With education and sufficient training, as well as opening dialogue between communities and the police force, police brutality can be controlled and reduced significantly. Look at Dallas, Texas for instance, former Chief David Brown was instrumental in opening up dialogue between the communities and the officers that served them. When the shooting in Downtown happened last July, we saw a unified city--one that refused to be torn apart because of one person whose sole intention was to kill an officer due to growing instances of police brutality.
There are times when force is necessary but in the case of a 91 year old, I doubt this person was much of a threat. The Internet abounds with video of police using unnecessary force. Tasers are used way too often. Many times there are enough officers to restrain the person with having to use a taser.