“Bears repeating: Not EVERYTHING that is odd is also relevant. “
Absolutely true.
However, if you are investigating a crime or putting together a case to prosecute or defend a criminal, or any investigating other kinds cases that involve looking at clues then you better damn well be looking at things that are “odd”.
For instance, a forensic accountant had better be looking for “odd” things. They may be relevant. They may not be relevant. But he had better not just brush them aside and certainly should not forget the oddities exist. The clue might come later to put the puzzle together.
It’s all about context, and it’s the context that allows you to determine what is simply odd to you and what is relevant. You can’t allow your focus to be distracted by completely irrelevant data.
For instance, the “devil’s horn sign” is an utterly laughable issue to bring up or even consider. You see devil’s horns, I see children. My own daughter does that very thing where she sucks her middle two fingers with her palm outwards. A photo of her with this is totally and completely irrelevant to a mass school shooting. Further, those of us with children know that humans are not born knowing what are considered rude or controversial gestures. I have seen family photos wherein it appears children are flipping the bird at the camera...they don’t know it’s rude. And what’s the implied cause of such signage? That the kids are satanic?
Any investigation must separate the noise from the signal. Do you risk filtering out some signal when you do that? Sure...but there’s nothing in other evidence to indicate that these particular issues are anything other than a typical American family being a typical American family.