I don't get why people are calling for a points deduction. I would be fuming if a Liverpool fan did that and the Club on the field was punished for it. I get that the blame lies with the Club because of security, but if someone wants to get on the pitch they are likely to get on the pitch at any ground.
Jail the guy and fine the Club, or make them play matches behind closed doors, but don't punish the players and the other fans because to them the points are all that really matters.
Maybe if it happens more than once...