I find it funny that this is offensive to some people. I cringe that some of the silly names we have given internal code bits or projects might one day offend someone somewhere and need to have a formal apology. It's a good thing people can't get under the paint of their walls as it's common for construction workers to write notes and draw on unfinished sheetrock.
It's not about leaving a humorous note or reference (I know I've left plenty), but that it's a sexist one reflects poorly on developer culture.
Please, I know it may seem like a minor point but if we generalize the term 'sexist' too much away from its origins, we will have to invent another term to define discrimination against women because of their gender/sex.
There have been arguements in the past about improper language having a chilling effect on women in the feild, therefore being indirectly discriminatory, but I don't buy it.
If you're not applying gender stereotypes, expositing hatred, or engaging in discrimination then you may still be doing something offensive, but it isn't pertinently sexist.