Firstly. Presumption =/= deliberation.
Next. Surely you know I am referring to the Christians, given that few if any non-Christians pay any attention to free will within philosophy? While the Greeks, specifically Aristotle I believe, were its originators, it was far less central to their overall program than it became to the Christians. Why? Because the Christians needed a source for evil that was not their god, despite the fact that their god himself confesses to being the creator of evil (Isaiah 45:7), and this is logically true, as it is unequivocal that god created both free will and Satan within the Christian mythological cosmology.
Next. Why class natural disasters as evil? Evil requires intent. If you indeed class natural disasters as evil then as the intent must come from some supernatural entity, and they logically and unavoidably must be considered evil. The events themselves are misfortunes, but there is no reason to presume a malicious intent behind them as we are no longer superstitious medieval peasants, one would hope.
As to the passive voice, I will use it when I please, as freedom of expression is an important human right, and I will thank you not to try to violate mine.
Next, I am referring to the evidence for free will as being equivocal. To clarify, unconscious mental processes that take place before thought formulation or action show that free will, like consciousness, is likely an illusion, hence the comment that it is a presumption, as most people, and indeed the law presumes we have free will. It is more likely, based on neuroscientific evidence, that in fact we do not have free will, but believe we do due to our lived experience, which doesn't allow us to properly apprehend our true condition due to unconscious processes being unconscious. While we can deduce unconscious processes when we see a person's consciousness break down during, for example, an episode of madness driven by chemical imbalance, during such an episode it is vanishingly rare for the subject to be properly aware of what it taking place to them, let alone within them, yet it is apparent to others.
Free will is the source of evil within a Christian world view. As to your question of how my framing of free will might justify moral evil, that is just a sidestep that I won't deign to answer. The historical facts as I see them, and I strongly believe I am not alone in this, are that the invention of free will as an explanation of the origins of evil within Christian Philosophy were driven by political motives to obtain more power over the public. If people believe that free will causes evil then they will rush to surrender it in any way they can (assuming that they accept the validity of the argument). This would be considered cult behavior if a small religious organization tried it. Certainly questioning Church dogma on the matter could get one tortured, whether by the Roman Catholics who were pro-free will, or by the Calvinists who were anti-free will. The sum of such behavior is tyranny, which is the abuse of power.