For one thing, this is being blown out of proportion, MASSIVELY I think. A lot of people don't lock their phones at all, so the same scenario could presumably happen to them. You don't see everyone warning others to make sure their phone is password locked just in case there are some sneaky kids wanting to put nudy pictures of themselves onto the device. In the US (and I think the UK as well, but I am not sure) there has to be proof that the accused is the one that willingly put the pictures there. The fact that the phone was left unattended for any amount of time, ever, would likely place enough reasonable doubt on the entire situation right there. Is it possible this scenario could play out as suggested here? Sure. I certainly wouldn't spend my time worrying about it.