If the uncle had no intention of putting away the dogs, he shouldn't have asked if the previous poster was scared of them. To do so was calling attention to her discomfort and then looked cruel because he refused to accommodate her. Whereas if he'd said nothing, he would have only looked ignorant.
As for kids overcoming fears, they do so best at their own pace. A child who is afraid of large dogs will only become more scared if he's pushed into a situation where he HAS to be with a dog. If, on the other hand, he's given control over how close the dog comes, how long he's exposed, and when he sees the dog, that will give the child enough control that he'll feel bolder about experimenting. That's actually the best way to let a child overcome a fear.
Think about it the same way as a fear of swimming. If you took a child who was scared of the water and tossed him into a pool, you'd make the fear worse. If, OTOH, you encouraged him to sit on the side of the pool with his feet in the water and watch others play, he'd eventually become curious. he might only make it onto the first step the first day, but over time he would feel enough control to descend another step, and maybe he'd ask to be carried in the water, and later to have a floatie pack, and so on. But at his own pace.
Forcing someone to ignore fear never made the fear go away. It only drives it underground and makes matters worse.
A child has no control over whether he's taken to a relative's house with dogs, so the relatives should be considerate of the child's needs. If it's an adult, the adult presumably has enough control that s/he can say, "Let's meet somewhere else" or "Please come to my place," and the pet owners should have less need to accommodate the adult's needs or discomfort.