[Q]

That is an interesting observation because I have seen AI empires using star destroyers (with stellar nucleonic torpedos) successfully rather frequently. Some of the designs had the cloaking ability, some not. Therefore I don't think the problem is the cloaking but rather the creation of a black hole itself. I never tried to make AI's create black holes (because I think the AI has more difficulties to handle a black hole system than a human player).