Babies are defensive not aggressive. He's in a new place with a new home and a new owner. Give him some time to settle in (no handling until he's eaten 3 consecutive times for you) and then begin short handling sessions spread out and slowly get longer and closer together. He should grow out of that behavior. Just imagine if someone took you, dropped you in an unknown place with an unfamiliar house and then someone was trying to manhandle you. I'd bet you'd be defensive, yes? I know I would. Just be patient with him and he'll come around.