If I factory reset my iPhone 5c, should it have reset the iCloud pin for the phone?

A couple of weeks ago me and my stepbrother was looking for some money so I grabbed my iPhone 5c which I haven't used since January and he factory reset it. We posted it on Facebook and this guy bought it. He's asking me "Ey sorry men the iPhone is have iCloud? The pin?" (yes he's Mexican). Shouldn't it have rest the pin for iCloud for the phone?

Added (1). This is what I told him "when me and my stepbrother factory reset the phone it should have reset the password so it should be whatever you want it to be"

You should have signed it out of iCloud before resetting it. Now you'll have to give him the password or enter it for him in order for him to fully reset the phone. There's no way around this (it's an anti-theft measure).