Umm... this was a figure of speech, not a technical limitation.
Originally Posted by David Grover / Hasselblad
"Leaf shutters do not work in a vacuum. Their speed is dictated by the aperture setting as well."
In other words, the leaf shutter is not independent of other factors. So, it does not "function" in a vacuum. Sorry for the confusion.
According to Leica, they will take the aperture effect into account and regulate the shutter so that if you have it set to 1/500th, it will fire at 1/500th regardless of aperture setting. I would be very curious as to the technical details of how the H system works and what the specs are.