Come on guys, this is all nonsence.
What is nonsense is when folks know a fact... which we all seem to agree that the fact is that the X-M switch determines the timing relationship between the flash initiation and the shutter "full open" position... and then imagine that they understand the mechanical way in which that is engineered.
There are a variety of mechanical ways, but all involve a detent - AKA delay - of some kind to get the M-flash initiation to occur 50 ms (nominally) before the shutter is fully open. There is a "mechanical slide mechanism" which is relies on the length of strip of metal to establish the timing; there is a clockwork detent mechanism, the Sychro-Compur being a classic example; there is a solenoid detent, like the Graflex system which uses movement time of a electromagnetic assembly to establish the delay timing
There are numerous patents throughout the 1960s and 1970s that used electrical circuits (timer circuits) to control the relationship between flash initiation and shutter opening. Many were simply electonic delay timers, but one I recently reviewed acutally computed changes in the overall shutter speed to compensate for flash bulb burn rate.
So it's not nonsense... it's ENGINEERING. Understanding how mechanisms are engineered trumps imagining how things work every time.
But we are only talking about milliseconds here... so lets not lose friendships over it.
[I won't even comment on your "fact jack".

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