Force ghosting is a relatively recent thing for the Jedi. We are to understand that the dead transform into the Force, and that this applies to all the Padmes and Bails out there, in addition to those Jedi who do not ghost. If Qui-Gon is telling Yoda a bunch of things he already knows, there doesn't seem to be much point to it. So it doesn't look like the issue of the cosmic Force and the netherworld works as the source of the historical schism between Jedi and Sith, especially given that there are much more obvious reasons at hand. We might consider how the pre-Disney EU addressed the situation. The question of whether ends justify means, as in the real world, need not have anything to do with the structure of the Force.
