After seeing the replay and reading Karthikeyan's explanation, it's a race incident. He hit the wet white line and had to turn right to get back to the tarmac. Then he hit Vettel, who wouldn't have been hit if he had left enough room to his left until the pass was complete. So both made a mistake, none of them intentional. I don't really know what the stewards wanted Karthikeyan to do, vanish into the air?