I think they are carefully posed photographs, that the photographer has taken multiple shots of the child looking everything from delighted to bored and everything in between, and then that the photographer has chosen the what s/he regards as the most emotive pics for the article.
I think that in the one of the mother and child the mother is having to arrange her face carefully so as not to smile.
I suspect that the child does not use her dummy very often during the day but, even if she does, so what? What surprises me in some of the reactions to the article is that anyone is surprised by the picture of a just four year old with a dummy in its mouth, as if childhood dummy-sucking were the absolute pit of disgustingness. This, to me, shows a lot of prejudice against children and a lot of unreasonable adult expectations of What Children Of Four Years Old Should Be Like.
In short, a lot of the comments are too judgmental for my taste.
So yes, those pics are acceptable. What's wrong with them? They illustrate the very contrived article (I hesitate to call it journalism) very well.