if prevention is defined on terms of intensity (i.e. shota/loli < CP < engaging in sexual activities with children < killing them afterward < eating their bodies afterward) then the activity (in this case watching animated child porn)is no lesser than what it represents via association
anyone can rape a woman and say "hey, at least it prevented me from raping her daughter" but is that rape really impeding said person from doing so or is it just a false sense of justification
maybe you should see a doctor, they have pills for everything now-a-days
I think raping someone isn't a very good thing to compare it to.. It's more like if someone enjoys watching rape-fetish porn and maybe enjoys a bit of roleplaying with their consenting partner. But never actually rapes someone, because they realize that that would be wrong.