The only evidence we have and nobody is saying there is any truth to it comes from a french film maker check Tim diggers post.

But the fact that many of Saws partisans feature breathing apparatus of some kind as well as saw’some iron lungs back this story up as something happened to this lot during the purge on genesis. I would go as far to say it has more to do with a failing death star project and lack of galens skills whilst also the major stall being somone destroyed a huge Kyber crystal on Route to the prototype death star to make this thing work. Or at least test it in some way. I think it ties up there is more evidence for than against. We don’t know if it is true. But it falls in to the category as did unkar plutt get his arms ripped of by chewie. We now know it was the truth. This seems equally interesting but also questionable.