Ps. Teams don't kick to the sidelines because the ball bounces out of bounds. Not because of what you described. Kickoffs are live balls which can be recovered by the kicking team. Downing a kickoff doesn't happen.
He maintained it by putting his hand on it and stopping it from moving. I can't imagine the rule stating he has to pick it up. If so, then as I stated above, the rule needs to be reviewed.
This is like catching a ball with one hand. Sometimes it's a catch, if you are OBJ, and sometimes it's not, if you are a Steelers player.
this is the NFL putting your hand on the ball and pushing it to the ground is not maintaining it...pick the damn thing up and show it to the ref...whats so difficult ..I actually kind of like the rule it adds something to the game