It's a bit like MAD. It relies on everyone doing the same thing. If an artist that normally posts lousy album sales doesn't put their seventh album on Spotify while all of the artists that week do have their albums on Spotify, I would absolutely call it dishonest if they scraped their way to the lowest-selling #1 album of the year.
Unapologetic wasn't even close to being the lowest selling #1 album of 2012. (unless you were referring to FF)