I'm doubting the validity of the proof. It seems to assume that there is exactly one least interesting article (the least interesting article). But maybe there are hundreds of articles that have the same lowest amount of 'interestingness'. I would say that then those hundreds of articles are uninteresting.
That's because they botched the proof. You need to sort the articles not by interestingness, but some separate canonical property, like creation date. Then you get a (here chronologically) first uninteresting article, which is interesting.
You assume A) that the set of interestingness values is both finite and discrete and B) that it's cardinality is extremely low. Both things can be remedied by defining a more comprehensive kind of interestingness that lets you compare more articles.
