"How awesome is your new program?" "So awesome"
Q&A session. People only think this transcript shows Obama stumbling with his words because they aren't aware that printed media cleans up the natural disfluencies that occur in speech. This transcript looks highly unusual, but that isn't because Obama's false starts and stops are unusual (they aren't). It's because it's unusual for them to be printed in a quote. Thus, the conclusion that the author is malicious. An attack on Obama for refusing to answer the question is fine. An attack on him for speaking like a normal person in a spoken interview makes no sense.
I would only disagree by pointing out that the President of the United States is not a normal person merely having a spoken interview. He's known as an excellent orator -- that's an important part of his job --, his speeches are carefully crafted and as you (seem to) say this is a softball interview. With all that in mind, why is he stumbling over a seemingly simple question?
Basic speech trick is pausing for a second, thinking through your answer, and then giving it carefully. This gives you time to avoid null words and ums and false starts.
If you're the POTUS, I'd be more than happy to give you a little time to think over your answers about surveillance questions before you bumble through them.