Comey KNOWS that his memos are “WORK PRODUCT”, prepared in the course of performing his FBI job.
He signed a Non-Disclosure Agreement both upon entering the service of the FBI and again upon his departure. That NDA makes very clear that ‘work product’ is government property and may NOT be retained or disclosed to those outside the agency.
It also was a felony for him to take a copy home and put it in his personal safe.