A packaging facility is not a fab. It doesn't really give them any advantage in reverse engineering the silicon over someone that buys the end product and de-packages the die.
I'd expect there's a huge validation stage involved-- flaws in the extraction process could give you a plausible looking but ultimately faulty design to work with, and you have to check and clean that up.
Moreover, if you don't have exactly Intel's fab technology and oral-tradition knowledge, you probably have to retool the design to be more suited to the process you have.
It might still be a boost over whatever they have to offer now, but by the time it hits the market, it would be a generation or two old.