It may have been pointless and it could have cost him everything, but it would have been RIGHT. So he should have done it anyway.
The kid in front had his back to the driver. He could have opened the door, grabbed that kid by the hair and the back of his shirt, swung him around so he was pointed at the stairs, given him a hard kick in the back to expell him through the door, and then closed the door. With that kid locked out, he then grabs the seat backs on either side of the aisle with both hands and swings his feet up hard, knocking the next kid backwards down the aisle and taking out the third kid with him. He then advances down the aisle, keeping those two from returning to the white kid. If they are on the floor trying to get up, he may even be able to get on top of them to keep them down. He would have had the element of shock and surprise on his side since from the video none of them are expecting the driver to do anything and are paying no attention to him whatsoever. Yeah, the driver was old, but so what? Do it anyway. He would have been a hero instead of a coward.