I am not sure if this was brought up, but why did someone argue that the historians/and everyone else would judge Shepard based on his/her actions? Technically, if Shepard chooses Destroy, he is the only living thing that will be around to tell that there were options. In fact, as far as everyone involved with the Crucible knew, it would eliminate the Reapers. If Shepard says nothing, which is not unreasonable if you are even slightly Renegade, everyone would most likely assume that the Geth (and EDI) deaths were an unforseen side-effect of stopping the Reapers.
Shepard certainly would not be blamed for it. He went in, following orders, nearly died/died, and eliminated the threat that was reaping the entire Galaxy. If anything, the blame would be on those that ordered the weapon to be fired, and even then.. saved total extinction, and all that. It is safe to say that no one knew what the Crucible would do, but everyone wanted it build because of what it COULD do. Even the Geth, if they are alive at that point, help out in its construction.