Robbing brand new players trying to fish (or do other mundane starting jobs) does more to chase people away than sporadic bouts of in-character sexism, but that's not going to go away. Just as an example.
The point I'm making is whether you want to call it "Grand Theft Auto" or not, you are playing on a server that enables all manner of terrible, heinous crime. People can already be absolutely terrible here through their characters, undertaking every bad thing you can think of, and they get away with it all the time. Demonizing specific aspects of this crime-ridden environment, such as sexism or racism, is a truly pointless exercise. It's even more pointless when nobody can give any concrete examples or propositions for rule adjustments, other than vague demands to end bigotry.
If players happen to express those sentiments in OOC, and you aren't okay with it, then there is already a rule you can cite to encourage the admin team to take action. Use it rather than limit the sort of characters you can play. God knows we don't need characters becoming even more generic than they already are.