I'm not quite sure how this attack can work because it has the following pre-requisites:

1) that you can generate blocks faster than the rest of the network

2) that you can do so without being subject to the same target modification rules

As I see it, assuming you have so much processing power that you can outpace the network, when you are doing your block generation, you will still have to adjust the target using the same algorithm or when you start posting your blocks to the network, they're going to get rejected because you weren't obeying the target value rules, therefore, I don't see how you could actually permit yourself to generate blocks more cheaply by not announcing them.