Reading the entire piece, or at least the surrounding text, one finds that it is merely a rhetorical device, not some final word.

Here are a few more snippets for those too busy or disinclined to read the whole thing:

"It was now clear to me that at least some of these packets were definitely forgotten orders. ... We couldn’t always come to a definitive conclusion. ... the USDA clearly remained unconvinced by my arguments. ... I certainly don’t rule out there being messier aspects to what happened last summer that remain to be uncovered."