I guess, having been taught to hand swing an engine from an early age, propellor dangers have remained a major concern whenever I'm near them. Propellers worry me, they have no friends.
We are creatures of habit, who see only what is expected so we can tend to naturally place ourselves in danger around Propellors. I'm dismayed now days at the complacency (or is it just ignorance?) I see on the Tarmac by CPLs and instructors: arms and hands passing through the prop arc, photos taken lounging against the prop and head-in-the-cockpit as the starter motor is engaged with a simultaneous cry of "clear prop" - but never a glance at the danger area.
In the days before Hi Vis vests, it was common practice to brief everyone on propellor dangers; especially visitors, passengers and students. I think the lessons, of the sad sad story, related in post #11 should be part of this briefing.
You don't need to be running the engine. Maintenance, especially if two or more are working, perhaps on separate tasks, can be dangerous.
When a father and son team were working on a C182 in Colorado, the starter accidentally kicked, decapitating the father. Both were fully qualified.