https://mason.gmu.edu/~rhanson/greatfilter.html
Authors. Hanson, R
Venue. — web essay, not peer-reviewed
How the Institute flags it
speculative 1 time handwave 1 time
This source carries more than one flag across the corpus. That is not an inconsistency to resolve: the same work can be established evidence for one claim and frontier evidence for another, and the flag belongs to the use rather than to the source.