No i think he can go into sage mode the only reason the two great sages were unable to attach themselves because while training to do so kurama was not in control (Note:- to go into sage mode you also should also hav to be mentally "eligible" ,nd thats the reason why kabuto nor orochimaru was unable to complete sage mode(as stated by kabuto)) they was not able to attach to naruto because of kuramas hatredHe can't because he is a Jinchuriki.