I'm not sure how that fits within the counterfeit rule. If they weren't the real papers at scihub wouldn't it be all OK? The issue seems to be that the problem (according to publishers) is that the real papers are available not behind a pay wall. The issue here isn't that the users of scihub are being defrauded by thinking they're ordering Prada and instead getting knockoffs. Not saying I endorse scihub BTW, just tha…
Interesting point. You could argue that a (good) counterfeit Louis Vuitton bag or Rolex provides the same functionality as the original, without the 90% tax to the rights holder. So, maybe the situation is quite analog: The paper you download is actually more or less the same as the original, but you haven't paid the rights holder, so it's counterfeit.
It's like I bought a bunch of Louis Vuitton bags and, for some reason, decided to sell them off for a fraction of a price. If you bought one from me, you'd buy an original bag, not a counterfeit one.