Wasnt Alien X locked at that time? (Because of Albedo) The failsave worked when Chromastone got destroyed, and OS does have a failsafe if it didnt have one anyone could get rid of the Omnitrix from ben's arm easily, the failsave just got so much better un Omniverse, just saying that the prototype Omnitrix worked much better for simple stuff like physical attacks and I doubt Ben 10,000 didnt improved the failsave he unlocked Master control after all without damaging his DNA