The great apes were certainly not meant to be captured by humans insulted by association, embarrassed by the involvement. They have advanced, social structures of their own, often more humane than what we have displayed. After all, they aren�t out trying to capture and domesticate every other animal on the planet. They are taking care if their families.
Monkeys; also advanced social structures, and not a great deal of difference than the great apes, perhaps intelligence proportion but still quite brainy and clever.
Think about what we do that makes monkey highly uncomfortable, for example you never make direct eye contact with them. It creates a fear response, can be considered hostile, or threatening. I first learned of this many years ago from a primate specialist who was watching me watch the monkeys. I could feel the monkey was uncomfortable but wasn�t certain why. It was the direct eye contact.
Now the chimp attack, the two women obviously were female. The chimp a male, it is his position as a male to dominate these females. As he got older it was well within his social structure to dominate these females with any means possible.
Cruel, but true. They had no business with a chimp. Well, at least the female �that owned� the monkey, the second female was simply trying to save her friend. I am not going to say it outright, but the chimp was within his own correct behavior determined by social order and structure.
On top of that the xanax could of enhanced the feelings of this dominate male ape.