if the engine is stopped with an idle cutoff which starves the carburettor, induction manifold and engine cylinders of fuel air mix, bringing it to a stop, then the propellor is as safe as houses [....] there is simply nothing in the cylinders to ignite.
If you stop an engine that has direct injection - like most constant speed engines - using mixture idle-cut off, you will most certainly be able to start the engine with mags-on and mixture still in the idle-cutoff position. In fact, this is the preferred start-procedure for warm engines.
It can be quite difficult to see from the outside if the engine has a carb or not, so don't count on the idle-cutoff theory unless you are 100% certain what the engine is, and how the previous user stopped it...