It is a small thing in the end but it is something that decreases trust and hurts credibility: Obama always being late--if you say that you are speaking at 0930 and you come out at 0956...that is just not cool. Obama needs to stop being on "Obama time" and rejoin the rest of us on regular time.
I want to go a little further; tardiness is not tolerated in the regular work place at all. If you are late on a repeated basis, most jobs will at least counsel you, if not release you all together. It is disrespectful to those you work with, those who are your customers, and yourself. It reflects a lack of care, consideration and planning that does indeed reflect badly on you. When you are late, you are saying a multitude of things most of which are not good; Disorganization, not having your act together, arrogance and self centeredness, for starters. I know that KMBZ has been inconvenienced by the president's lateness several times; just about all of his daytime speeches end up on "Obama time."
So President Obama, be a man of your word. When you say 9:30 a.m., show up at 9:30 a.m. It means that you are ready, willing and able to competently do your work. That is a standard that the majority of us in your audience have to fulfill daily.