I believe it is impossible to be that incompetent. You could have taken anyone off the street with an average intelligence and put them in the advance team for that rally and the first things they would have noticed are the rooftops of the buildings and the water tower. The Secret Service was in on it.
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I agree with every word of this. To say this was incompetence is like saying a professor of mathematics who can't tell you correctly what five times three is is an incompetent math professor. No, that is not incompetence. Either the professor is refusing to give you the correct answer, or he is not a professor, or something else. But it's not due to incompetence.
And yes, anyone could have done a better job than they did with just a little common sense.