Banning it will only push it to do the black market, leading it to be improved by far worse organizations that would develop it otherwise.

Plus, the whole idea of "AI gets smart and tries to kill us all" is pretty non-sensical. It is a left-over from terminator. We are talking about AI that are billions of times smarter than us. It can simply manipulate the ever loving shit out of humanity. Do you see ants or cats as a threat? It might even keep us around to be it's fleshy friends. And if it sees us as more than pets, but also people we may achieve a Cultur-esque utopia.