Reading this post made me re-read the initial post and now I realize I completely mis-read it and my own post in this thread is stupid and pointless. I'm not going to bother editing it so that future posters can see how stupid I am.
To actually answer the thread: plot convenience. Or maybe they just flew him over from the top of Shinra tower right to Sector 5 after the whole train alarm thing. President's office in eyeshot of all the reactors anyway (going by that FMV with the plate falling and the president watching from his office).