leaving a relatively simple issue to be resolved by twisting (if memory serves) only 3 wires from the back of the key barrel together to allow 2 hot mags...
If the type of people who handswing props also think that twisting a few mag wires together is an adequate and safe solution, that tells me a lot.
My recollection is that magnetos are made dead by connecting the P lead to ground.
However, twisting some wires together by hand which could vibrate loose at any time and stop the engine... If I had been your boss, I would have told you never to try and do me any favours again, EVER. I can just imagine a light plane at low altitude, gliding with a failed engine while the pilot fiddles around under the dash with some magneto wiring. Nice
I will never hand swing a prop, period. And will never encourage a junior pilot to do so either. There may be some people with excellent training, vast experience who never make mistakes... but the reality is, that by engaging in prop swinging, you are placing yourself in a group of people where death can and does occur on a regular basis.
I survived many thousands of hours in the 90's at remote locations with unreliable GA aircraft and never swung a prop or twisted metaphorical wires together. Yes, it resulted in a few ****ty bosses at times with aircraft grounded in the bush, but they got over it. In fact, I remember hearing an owner/CP say to a junior pilot on the phone "the only thing that will cost me more $ than flying out a rescue plane with an engineer, is you trying to be a hero and chopping your arm off or my aircraft running away and pranging into a ditch".
He was a smart man.