Re: Didn't realize this is a rule about spiking the ball.
I think that applies only after the down. You're still allowed to spike the ball to kill the clock. (The highlighted question seem to apply to a delay of game, like kicking the ball after the play is over. Anything that slows the game down or makes the refs run to the ball).
They did add a rule that says you cannot spike the ball inside of 3 seconds, but I think that rule is a bit loose in its enforcement (I.E - I dont think the officials will really call it unless there's something weird in the game that necessitates it. Like maybe... if they were lining up for a fieldgoal, there was a bad snap, and the holder spiked the ball before the linemen got there).