Ian, I have worked in this field.
The idea that "it is few statistically" is simply false.
I don't understand on what basis it could be argued that "even fewer ... use photography"
The point being that abuse within families is a significant and horrible problem that has remained untroubled by public attention; most attention is given to the (truly) few (statistically speaking) "strangers" who abuse children, which allows the rest of the population to maintain the fiction that "this doesn't happen in families".
Fortunately, this is changing, albeit slowly. One effect of that change is situations occur like that of the OP, where someone's judgment rather failed them.
However, if inconvenience and unpleasantness for someone like the OP is all that has to be suffered, that's fine by me. It proves that people have had their eyes opened.
I think you miss most points, the issue really is what's normal and what's deviant, my take is I have tfriends whom have been abused and photography isn't/wasn't an issue.