She wouldn't happen to have been ethnically malay and muslim by any chance? They are muslim by constitutional decree in Malaysia, though not, of course, in Singapore.
I am not sure if Islam considers monkeys unclean in the same way as dogs, but I suspect it does. While in Singapore, I witnessed the huge outrage that ensued when an acquaintance called an ethnic malay a dog, not without justification given the latter's behaviour at the time.
I do know, however that hatred of monkeys is widespread among at least the more red-necked malays.
This is as a way of getting at the ethnic chinese, since monkeys have a special place in chinese folklore and religion, both folk religion and the sino-buddhist tale of the mission to Ghandara.
In more than one case in the past, monkeys in public places were poisoned just to spite the ethnic chinese.
By the way, it isn't wise to generalise from 'Malaysia' to 'south-east Asia'.