The association of "Aryan" Germans with being shredded and people who are trans, autistic, etc. being positioned as the opposite. Eugenics is the idea that some people are genetically "superior" to others, making "Aryan" babies was a big part of it, but that's the main idea being referenced.

As somebody who is autistic myself, it doesn't feel right as a "joke". Yes, it paints people who believe in that sort of thing like idiots, because they are, but this is programmer humour, jokes should be about programming things! Off-topic and generally unfunny in my opinion.