Sorry he is flat out lying that he didn't know about it.
I agree. Knowing everything about the people who work under him--and especially knowing about their security clearances, or lack thereof--is part of his job. And Porter was his assistant; pretty much the deputy chief of staff.
Do you really think Porter was going to ask?
If he were really innocent, as he claimed, he'd have welcomed the opportunity to explain.
Yesterday CNN interviewed Linda Chavez, who was nominated to be Secretary of Labor in the Bush administration. She'd had a problem with her own clearance. Evidently the FBI, while doing its background check, had learned that ten years earlier, an illegal alien--a woman from Honduras--had lived in her home. Chavez hadn't thought to mention it in the forms she filled out.
Evidently a neighbor for whom the woman did cleaning ratted Chavez out. The woman also looked after Chavez's home, and in return got room and board and additional spending money. When confronted with this, Chavez simply admitted to it, and withdrew her name from consideration. She said she'd learned that the FBI is very thorough, and was surprised Porter had been hired at all.
Chavez is not impressed by Kelly's performance on the job: