Although blurred out, he was clearly referred to as a POI in the SN episode featuring KT.
Regarding the photo where people believe there absolutely must be another person unaccounted for due to the direction William is looking in, he was roaring! Imagine a child imitating an animal sound, they usually "get into character" & act it out with their whole body, not just their voice boxes! William was probably displaying his ability to "roar" & mimicking the way we see cartoon tigers exaggerate this behaviour.
Also, I am an amateur photographer, taking photos of animals for a hobby, I cant tell you the weird positions you will find yourself in while trying to take a photo, even extending the camera/phone away from your face area to capture a certain moment, IMO if there was anything in that photo sinister, or anything that pointed towards an obvious indiscretion in what was reported that day, they would have used another photo, apparently that was one of three taken that morning & we have all seen the amount of other photos of William, they certainly weren't short of photos!
Regarding the photo--I was thinking of that too. I sometimes play at roaring with children. When you roar, the head moves up and also the eyes as the mouth opens; there's an arching of the back or at least the neck.