Well, in that case the rationality is low: one can't even figure out that for given death rate others got to be very predominantly surviving similar threats, or successfully avoiding those threats at even earlier stage - the average 'SA' is apparently good enough.

Basing really strong results on really weak evidence (and generally overestimating strength of the evidence) seem to be a pervasive pattern here, though. Even in the cases where choice of prior is straightforward, such as for intelligence expressed as rarity; people either overcome some seriously low priors with some seriously subjective and error prone evidence, or maybe fail to even have priors.