I always thought the physics on that one was a little shaky. We know how EM radiation of various frequencies and intensities affects biology but neutrinos are not EM radiation. The paper Munroe cites mentions that it ignores the expected supernova neutrino spectrum and its consequences with regards to biological interaction specifically because the dose is so low at the distance with which the paper is concerned, 1 parsec. In a scenario where one's objective is to calculate the lethal distance, that spectrum is important and may wildly change the results.

It's a fun read but it's bad science.