Maybe I misunderstood the twitter quote - it seems to be saying that this “surprise” has to do with college applications for financial aid. In that case, for Obama, the tax form would be from the late 1970s or early 1980s (Occidental or Columbia) or the early 1990s (Harvard).
The 1982 1040EZ is the oldest 1040EZ that the IRS has posted on their website.
But come to think of it, a college application for aid would probably include a tax form from the parents/grandparents of the applicant.
Uh oh. Who is the father?