1. women are too delicate to handle any references to anatomy
2. the "jokes" were simply crude and, while off-putting to anyone with a developed sense of humor, nothing to write (tweet?) home about with regards to being offensive
So I can imagine sexist-seeming jokes about robots with dongles, but I can also imagine stupid ones about robots with butts or whether car exhaust counts as a robot fart. The sad thing is that we have no way to tell whether the remarks in question were sexist or just stupid, and that has encouraged a lot of folk to just project their own preconceptions onto the entire incident.
This sort of thing is exactly why I don't like using Twitter.
(disclaimer i am female)