By Gatlin's own words, he did not belong racing there. He talked about cramping up after Doha. Anybody who has been a sprinter, coached sprinters, or knows much about the sport is going to know that 4 days is not adequate time to recover from a PR/statement kind of race and the 6th fastest time ever run. Even a week would be pushing it. Go back to the 2008 OT when Tyson Gay ran 9.68w and see what happened in the 200m prelims a few days later. Either Gatlin would have to "jog" through in, say, 10.05 or he's going to get injured. And the get injured part is probably what scared the Chinese, because that would mean no Bolt-Gatlin faceoff at their world championships. Go to Rome, go to Ostrava, go to Oslo even, but AFTER your body recovers from 9.74.
Another thing that has not been discussed here is that Renaldo Nehemiah is perhaps even a more polarizing figure on the circuit than Gatlin. He has a bad attitude and a LOT of people (including a lot of race directors) don't like him. It would be just like him after the 9.74 to ask for a lot more appearance fee after they already had an agreement. It would not surprise me at all if that is the real reason for Gatlin being kicked out.