This is pretty typical behaviour for a new snake. The fact that he's calming down once he's held for a while, means that he's gradually getting the idea that you aren't dangerous.
There are some things you can do to minimise his problem with being picked up. Never swoop down on him from above - this is predator behaviour and will make him defensive. Approach him from the side, very slowly. Make sure that he know's your hand is near him before you touch him. Sometimes they can seem alert, but actually be unaware that you're near them. Don't make sudden movements near his head. Wash your hands before you handle, to clear traces of smells that he might find intimidating. Apparently CK1 cologne (and Impulse body sprays for the ladies) contain pheramones that can turn the mildest Corn into a nightmare.
Over time, he'll be as relaxed about being picked up, as he is about being held. All it takes is time and patience. Sounds like you're already half way there.