They get used to a certain way of doing things and anything unusual is considered a threat. This is why you always mount a horse on the left side. My bet is he will get used to his situation and chill. All my adult ball pythons have been taught to eat a dangling rat. When I put one in and do the zombie dance, I get some unusual reactions.
I would take him out and put him in over and over again till he got wise to the situation.