It doesn't matter what was scheduled. You obviously don't work for the government or understand how things work. When your "big" boss wants something (here it would be the 4-star general), you jump through every hoop to make it happen... that's the way it is. It doesn't matter if it is unethical, illegal or causes you to work 5 hours overtime with no pay. Obama is the PRESIDENT OF THE UNITED STATES. It doesn't get any higher. The Speaker of the House, the House, the Senate, etc all work for him. If you already had something planned you move it to another day. That's how shit works.
Now, in all reality it was probably no big deal for Obama to move his speech to the next day, however it isn't about what makes sense or what causes the least amount of issues with current events... you have an image to maintain and part of that image is a projection of power. Obama already looked weak against Boehner because of the budget debate deadlines and now he's looking weak again bending over to Boehner's schedule. To the average American it makes it look like Boehner is running things, not Obama.