Huh, that's strange. I believe that's the only counter to any instant removal abilities. I can abide by the rule, but I don't agree with it.
Even stranger is when Boon of Mutation occurs. When a Toughness test is failed, the model is removed as a casualty *or* replaced by a Chaos Spawn. Presumably, if replaced by a Chaos Spawn, Reanimation Protocols would not work, since the model specifically is subject to an effect different than removal as a casualty.