It is not uncommon for imprinted guineas to start attacking people once breeding season arrives. Most people with similar stories to yours have very different stories once they get through a breeding season.
I have never had a problem with my Guineas being aggressive towards me, not even during breeding season. I usually have somewhere between 10 and 20 Guineas and in the 4 years I have had them, I have not seen any behavior changes toward me during that time. Some of my Guineas are more tame than others, but all of them will follow me around and come running when called. The only aggressive behavior I see in mine is the hens being protective of the keets, and this is usually short lived and only a problem when they feel the little ones are in distress (if I pick the keets up and they are screeching and squawking), which is a protective behavior I can appreciate as they are looking out for their wellbeing.