As the ball was not travelling towards a Dons player or the goal it is not deemed to be a bookable offence. Had to look it up myself as was convinced it should have been but saw the above explanation being given as to why it was not.
Copy of FIFA rule below
Cautionable Offense
A handball should result in a yellow card caution if a player handles the ball for the purpose of deliberately preventing an opponent from getting possession of the ball. The resulting restart to play should be a direct free kick from the spot at which the infringement was committed for the non-offending side. If this occurs inside the penalty area, a penalty should be awarded. - See more at: http://www.livestrong.com/article/123838-fifa-soccer-rules-handball/#sthash.ldnQq7og.dpuf