It will happen again and again too. If it was skill based and something you could only do weekly or monthly then he'd be wasting his time doing that.
But no. People insist on having leaderboards time based which are the most likely to get done over by acts such as this.
In one way I feel sorry for ND I know some members of staff were working hard on those leaderboards this weekend... On the other hand though I could have told them it would happen. I actually predicted the timeframe near correctly on facebook.