These two investigators are more than a little hapless: they disagree and lose focus. In fact, they seemed more like a comedy duo than serious dudes investigating a tragedy.
But they fulfill an important, though limited, role in the novel. They're the agnostics of the book and perhaps mirror the response of the critical, secular reader. It's telling that these two want to know the "straight facts" of the story – and not only the facts, but specialized facts that will explain the mechanical failure of the Tsimstum. They have no interest in a surprising, beautiful, messy story.
However, when Pi tells them an alternate version of his story – the horrific, abridged version – they change their minds. "The story with animals is the better story," Mr. Okamoto says (3.99.432).