Tom, without getting too heavily involved in semantics, it seems that
Portraiture is the act of creating a
Portrait.
The artist, Justine Varga, was quoted as saying ... "She was quite bemused that I asked her to inscribe on the negative and basically spit on it," she said. "You know, she's my grandmother. She's not really into that sort of thing."
Her winning entry,
Maternal Line, may have 'artistic merit', but I fail to see how it can be considered a portrait, and one that can be identified as a representation of her grandmother, without an accompanying description.
Surely Photographic Portraiture doesn't need an addendum to tell the viewer what they are looking at.