That's certainly /r/news' justification, but their argument doesn't wash. It's no more opinion than any other piece of investigative reporting - they all tell a particular story through the facts they select, how they describe the issue, and the conclusion they draw.
But IS investigative reporting "news"? Traditionally they've been bundled together, and there is undoubtedly overlap (depending on the piece), but at their core they could be considered quite different.
If you exclude investigative reporting from "news," then that means that the veracity of news is predicated on perfect trust in institutions. You must assume that all the pronouncements and press releases of governments, corporations, and interest groups are completely honest and accurate.
Or to maybe put it even more bluntly: If you don't consider investigative reporting to be news, then "news" becomes a synonym for what we would generally call "propaganda".
Which the beloved "objective" news does, uncritically rewriting press releases and cheerfully transcribing whatever spin government figures like to give under cover of anonymity. Because, and let's be blunt, "objective" news is what partisans call reporting about politicians they like that doesn't make them uncomfortable.
90%+ of "news" is regurgitated PR. Original reporting, including investigative reporting, may seem out of place in that context, but it is much more accurately called news than what is usually fed to the public.
