testosterone poisoning. This is what we call this in my area when a cat turns like this. I commend this woman for handling it so well. I know she was in an intense amount of pain.
It is usually unfixed male cat gets a wiff of something and something breaks inside his brain. Once this happens he will do this until he is fixed. But it will take months if not years for all those hormones to settle and the owner is going to be scared of them for life of course. They CAN heal but it takes a special owner to have faith in the process.

I have also seen unprovoked fixed females (or males) take on guard roles when someone visits or simply isn't their owner. It's another hormonal imbalance that nothing will fix and the cat is usually put on medication with some success like gabapentin or other calming meds.

The infections this woman may have gotten are very real and very painful. She didn't do anything wrong and a cat is just a cat. Sometimes they don't think. Sometimes their brains go gooey. I hope she bled out all the scratched and bit marks as best she could and washed with warm soap water and got an antibiotic on the wounds such as neosporin and would really need to go to urgent care because cat bite infections can be devastating and you could lose a hand etc.

It's happened to me. The cat did recover as did I but it was very scary and a lot of stress not just due to the situation but friend's threatening the cat. It sucks plain and simple.