The problem is that according to the dogmas of most forms of Christianity, God is not merely benevolent, but Infinitely Benevolent. The situation you describe would fulfill simple net benevolence, but Omnibenevolence requires much much more.
Well, I did say that the scenario being described didn't neatly fit within the Christian perspective. And there
are valid ways of reconciling omnibenevolence too, bu they also won't neatly fit into the typical Christian perspective. For example, what if we expand the analogy to include the concept of reincarnation?
If so...then any conceivable
earthly horror can be easily reconciled with divine omnibenevolence. If you're an immortal spirit consciousness going through incarnation after incarnation...it's not such a stretch to suggest that at some point you might simply get bored of lifetimes filled exclusively with butterflies and bunny rabbits. Humans sometimes like to watch action movies, horror movies, etc. You go in, you get an adrenaline rush for an hour or two, you leave and go back to whatever you were doing.
If you're immortal, eternal consciousness...is it really that difficult to imagine being willing to do a quick 30 year lifetime when maybe you get raped and murdered? Then you're done and you go do something else. No big deal.
Ever gone to a movie without watching the previews? If you're an immortal, eternal soul who's experienced dozens or hundreds of lifetimes...how closely do you think you read the fine print in advance of every lifetime? Is it such a stretch to imagine that you might try incarnating into a body with a "surprise me" lifetime attached?
Divine benevolence is totally not at issue here. It would be no more "benevolent" for God to step in and stop souls from doing this kind of thing because they might have an unpleasant experience than it would be for someone to ban horror movies and stop you from seeing them because you might get scared while watching them.
It's just a question of perspective. Many things change once you make the conceptual shift from "I am a human and this is my life" to "I am an eternal conscious spirit being having a very brief visit here on Earth."
Anyway, if you want to answer questions like these from a "traditional Christian perspective" I think you pretty much have to fall back to answers like "Just have faith. It all makes sense, and God is perfect so no mistakes will be made. Maybe it doesn't make sense to us as humans, but it doesn't need to and we don't need to understand. All we need to do is have faith in Jesus."
Some people are happy with answer like that.
It's not my intent to be disparaging, but my impression of Christianity is that it's basically an imprecise religion. It's like a crayon drawing without a lot of detail. You can see the general picture, but the finer resolution just isn't there. Some questions about "what Christianity's dogma is about X" can't really be answered because it doesn't address X.
It might sound "weak" for a Christian to give an answer like the one I suggested above: "don't worry about it, just have faith in Jesus." But that doesn't necessarily make the answer invalid. If I ask you divide 5 by 3, "1 remainder 2" is a valid answer. Christianity seems kind of like that to me. It doesn't really say what to do with the remainder.