Courtesy of Allah, I see this....
As you will note in the upper right, I am an airline pilot. This may not be obvious, but this means that I fly with a number of different First Officers all the time. Occasionally, I will fly with a different F/O on each leg. I cannot tell you how many times I've looked over to my right to a guy who I have been sitting next to for the past two days, and silently asked myself: "What is his name?". With Flight Attendants, it is even worse. I have only a cursory exposure to them...frequently not even meeting some of them at all.
That said, I've always believed it is important for "The Boss" to at least know his subordinate's names. And, since I know this is a weakness of mine, I know I have to work to make sure I do. I don't always succeed (especially with the F/As), but I do try.
And as myrenovations notes, for the President of the United States, in an address on National Security, to mis-identify the Secretary of Defense is "awkward", in the very least. For him to make this mistake in the presence of his famous teleprompters is doubly awkward and unforgivable.