The point that many of us took issue with wasn't the issue of propeller safety it was the issue of how a well intentioned photo turned into another aviation pi$$ing match. Also the practice of passing judgment based on photo when you can't possibly know all the facts of the scenario. This post is a further example of why some people got annoyed. You say the kids were hanging off the prop? That's not even close to accurate and now people that haven't seen the photo assume it to be true.
The point is, if you see something and feel it's a safety issue, then approach things the right way. The way you would approach them if you saw it in person. Pull them aside, ask for clarification and make sure they understand the risk. That doesn't tend to happen on the Internet for some reason.
No with that off my chest, thank you for the post. A post on a forum like this about an important safety issue like this is a good thing. On this specific topic, I'm not sure what others have experienced in training, but there sure seems to be some variation. With lycoming engines I was taught about the risk of the engine firing and to assume it will fire if the mag clicks, but it certainly wasn't drilled into me to never touch the prop or stand within its arc.
It would also be useful to talk about the variations in engines and engine systems and how it impacts the likelihood of the engine firing.
So for example, carb vs fuel injection, hot vs cold, mags off vs on. I guess the key is, many of us would assume that if the mags were off or if there was no fuel in the engine then it wouldn't be possible for it to fire, but maybe there are surprising situations that we should be aware of?
Anyway, like I said, a good topic and a valid point. The only thing that annoys many of us is how quickly the conversation can take the tone of an arrogant yelling match rather than a hangar conversation amongst friends.