In fairness, Michael Arnt had no script almost one year into his hiring. Ideally they would have given him more time to crack the story but with the short schedule they were given I don’t really blame them for getting rid of him. It’s just that JJ should have been kept far away from the script.
*no completed and approved script.
It’s not like he was twiddling his thumbs. He was doing what Abrams wouldn’t: putting thought into the script.
He was working with Abrams.
He was fired when Abrams was hired and said he wanted to do the script himself, he brought in Kasdan, and they kept the protagonist being a girl and Luke being at an ancient Jedi Temple. The plot and story was thrown out to make Luke a maguffin and to mimic A New Hope.