Shouldn't this be called "Gender Machine", they get it right on the project description but not on the project name, weird.
Determining the boy/girl-ness of a chicken is called "sexing" the chick. I see "sex machine" as a machine that sexes by name.
The code is using the gender of a reference to determine the sex of the referent.
So you could say that they're both right.
So, I think 'sex machine' is appropriate.
[0] Okay, three options, but 'andy' really corresponds to 'unknown', not 'person of androgynous gender'.