That line about Luke sort of bothers me too sometimes, but I rationalized as meaning that Luke led the efforts to find a new base (perhaps using his rogue squadron), not that he was in charge of thw whole base. It's obvious from the film itself that General Rieekan is the military officer in charge, with Leia as the highest of the political branch.

Of course it would be possible to change the scroll to "a group of freedom fighters, guided by Luke Skywalker..." But I'm not sure if it should be done.