sorcery on teemo is not granting ap unless u buy ap items

Not sure if this is intentional but when piking sorcery on teemo he only gains the ap bonus if he buys an AP item, if u want to get something else, such as boots, u will be stuck with the ad bonus only ( at level 1 or untill u get some ap item). guess this might affect other champs, in a diversity of build wise runes as they were sold as, i guess there should be some way to choose wich bonus u get in case of hybrid potential champions.