The Rambam was a big reader of Aristotle and other Greek knowledge
The idea of no Chachmas goyim actually comes from the Chasam Sofer, While I am not going to question the Chasam Sofer, there are plenty of Gedolim who disagree with the Chasam Sofer. If you want to follow the Chasam Sofer, that is fine but dont expect everyone to hold by him.
And BTW My ancestors came from the Ghetto too and thats why they left. and the word Ghetto itself comes from the Foundry in Venice which was the first Ghetto.