Adorable little boa you have there.
It is so cute when they "reject" things, like the way he's rejecting his hide. My bci will let you know if he does not like something you put in his tank, like a new hide; the neck goes into a S shape, like in your third pic, and then turns sharply away as the snake looks for "greener pastures" elsewhere. Gotta love snakes that are that picky!