Though I still need to know his body language when he gets aggressive, if he were my ig, Id go so far as to not allow anyone to look straight at him. You also may need to learn how to pick him up. Do it from the side, and do it quickly. The best a slow moving hand in his habitat can do is to freak him out. Even though people do use that as a taming method, I regard their igs as exceptionally easy-going. Does he run up your cloths to bite your face, or does he just open his mouth?
IMO your ig needs to be trained/tamed. Start by picking him up (from the side, using your peripheral vision) at least twice per day, three times would be better. It's normal for igs to react violently at that, but hold him with both hands until he stops struggling (takes about 30 seconds). Then sit down with him, never letting him get away, for 10 to fifteen minutes at this point. Then quickly place him back into his habitat.
This is a useful nugget of advice, but there is more to learn about taming. IMO, at least he's eating and drinking. That keeps him safe during a many-month taming effort.