The villains in this story (ratings agencies) had lots of models, bad and good. They chose to publicly report the ones that suited their interest, rather than the most accurate ones.

The way to improve the situation is to educate the consumers of those models (securities purchasers) about what models are best, and which are misleading.

It's more productive to say, "Buyer beware, sellers are misleading you in the following ways..." than, "Shame on corrupt sellers!". Silver's book is doing the first, which does not constitute defense of corruption.