No one in the picture or the audience is sexualizing little girls (or boys). Instead, the outrage is caused by harmful expectations of purity that are imposed on girls and women, but not boys. As well as the current moral panic about pedophilia, which again is unhelpful in actuality protecting children.
Want to protect help children from predators? Help them remove the stigma around their bodies and sex, and empower them to speak and be heard when something they don’t like happens. Failing to do so reinforces the feelings of shame that all too often enable predators to get away with what they do.
And maybe also don’t share potentially embarrassing photos without consent but that’s small potatoes compared to the above issues.