Several points to consider and it is hard to be definitive without seeing something like this.
1) the center can touch the ball and adjust it so he is comfortable as long as he isn't picking the ball up.
2) he can release the ball, as long as he does so in a manner that does not simulate the start of the play
3) if he moved the ball in a manner that simulated the snap and brought it back (double clutch) that is an illegal snap
4) the defense cannot slap, hit, etc the ball during the snap
So, any illegal snap/false start by the offense would be a dead ball foul, so anything that he did illegal (center) would have killed the play.
So if the defender just grabbed the ball and took off, they could have flagged him for either offsides or delay of game for running off with the ball. 5 yards either way.