I agree that these all these remarks were carefully prepared. Brady and ownership certainly were not surprised by anything Belichick said. In fact, it seems clear to everyone that the comments were not "normal" Belichick. Every analysis that I have heard indicates that this is Belichick's longest uninterrupted statement on any matter. This just wasn't Belichick's style.
that being the case, Belichick could have said many things. He could have said that, as coach, that he is responsible for everything that goes on. He could have said that he is investigating and he will find out exactly what happened and discipline folks appropriately (last time a cameraman was fired). But Belichick did none of these. He used his prepared comments to make a Sergeant Schultz replay to the situation "I know nothing". Further, he basically said that it Brady who would know about everything to with the football.
Some characterize this as throwing Brady under the bus. In any case, Belichick absolved himself of all controversy (similar to what happened at the college level when this issue came up).