If English isn't her native language, it's possible that she just can't understand what he's saying. People outside a little kid's immediate circle usually have trouble understanding what the child is saying. In fact, speaking clearly enough that a stranger can understand is usually listed as a developmental milestone.
It can be very hard for a non-native speaker to understand non-clear diction as it is, so adding normal kiddie ways of speaking (e.g. lomoCOtife) could just make it next to impossible for her to understand (not her fault; it would probably be the same for you listening to a very young child speaking a language that was only semi-familiar to you).
