All of his colleagues respect his insistence on maintaining his own private space, and play along with his "walls" charade. Mr. Carlson even "knocks" by clicking his heels together, although Jennifer is permitted to ignore the imaginary walls.
Mr. Carlson maintains a strong sense of privacy, which is respected by his colleagues. They engage in a lighthearted game where he pretends to have walls, and they play along with the charade.  Jennifer is exempt from following these imaginary boundaries.