Most of you are being childish. A coup is planned by keeping everything in mind and the number of soldiers/ninjas present for guard. The uchihas were not idiots. Do you think they had not thought of any scenario and were simply going by a stupid logic of, 'hey guys, we'll attack, like tomorrow night, if we get our asses handed to us, we'll hit the drawing board, kay?'
They were planning a coup by obviously keeping every factor in check. A hyuga is only useful in this light, if he/she is even using his senses and is awake. A coup is done in a very very sudden, hard and fast manner without any suspicion, so the uchiha at the guard would initiate it first, bringing in the support groups to take out the guards to the elders quarters and the hokage room, so on and so forth. Every factor is kept in check for a coup. They were planning this for quite a while, and obviously had planned out all the possible out-comes.
