It does no such thing. Nor does it even really purport to. Its explicit purpose, rather, is to narrowly refute the Obama campaign's "very serious charge of potential criminal behavior" on Romney's part, which is indeed serious, but insignificant compared to the Obama campaign's political indictment.
Concedes WaPo's Glenn Kessler: "We readily admit that there is grey area about Romney’s involvement with Bain in the 1999-2002 period."
But here's the much larger point, which can easily be made by any objective observer: Romney could clear all of this up by simply releasing his pertinent tax returns.