Also, here's a writeup by one of the authors explaining the history and context behind this paper: http://www.wfnmc.org/mc20101.pdf

Apparently the question posed in the title of the paper is still an open question, although both authors conjecture that the answer is "no".

There's previous discussion on HN (2015) but I hadn't seen it before: https://news.ycombinator.com/item?id=10622660

I found out about this through this stack exchange answer that also lists other candidates for "shortest math paper ever" by various metrics: https://hsm.stackexchange.com/a/14612/18150