I think the first choice the American director was Spielberg, but since Lucas left the DGA, and Spielberg was a member he could not be used, i am sure Lucas tried to work something out and was unsuccessful. Lucas had a hell of a fun time doing raiders with Spielberg and described it as the best possible collaboration experience.

He also tried to get Ron Howard to direct the Phantom Menace, and wanted Spielberg for possibly attack of the clones or revenge of the sith.

Still Lucas never returned to the guild and he still has yet to let the grudge end.

Also word got around Hollywood just the allegedly atrocious way and controlling manner Lucas had treated the other directors, on empire and on jedi, and so no director even if Lucas was in the guild would touch it. The man's ego was a huge obstacle.

For the longest time he and Francis were not on speaking terms either according to Skywalking because of the the size of the two griant egos.

He has never amicably patched things up with Marcia, somewhat understandable, but his grudge against kurtz, and Prowse make no sense.

Wonder if he ever patched things up with milius probably not, he never did patch things up with Dykstra.

You either supposedly follow general Lucas orders or you are out of his circle forever.