He doesn't need a live composer ... he has his computer, and the legal rights to do whatever he wants with the music previously composed by John Williams for any of his StarWars (TM) movies.
Rumors of this get my blood boiling.
I happen to think The Imperial March is a little too specific and lighthearted as compared with the very brief and moody coda written for the Death Star and the Imperials in Star Wars. It's a neat theme, but sorta silly. I like the way it's used constantly in the Empire score, but it was wise to subsequently put a lid on it in all subsequent Star Wars movies.
No matter what you may think of it, and I'll admit it's an iconic piece of music, nothing Williams wrote for Empire, Jedi, or Episodes 1 thru 3 hold a dim candle to the pure unadulterated GENIUS of his Star Wars score ... and if George Lucas mucks with that ..... (well, I suppose Death Threats can be taken the wrong way on the internet, so I WON'T be making one).
But damn him and his twelve necks to Hell.