How to deal with an old perv?

Here is my dilemma. I live in an apartment complex where everyone minds their own business. There is a really old man who walks around the complex all day, every day, with his walker. When I first moved in late January, I started talking to him because he was the first to be welcoming to me. I like sitting on the porch and breathing in the nice clean air, and he would stumble up with his cane or walker and sit and talk with me. Then he started getting vulgar, making me very uncomfortable with the crass language he would use, telling me "I want to eat your *****" and "how is your ***** doing?" So, I made 2 complaints to the landlords who basically told me "he's a harmless old man, I don't know what else to tel you". I don't sit on my porch anymore because I don't want to talk to this nasty old man. A few friends have said that he is old and feels that he has nothing to loose by being perverted with a 30-something woman, yet I still have a right to live a comfortable life without this intrusion. I miss being outside, and I hate this dirty old man for making me feel scared in my own home.............how do you deal with this???