On a positive note, it was a lighter and not a coconut (seriously what were they thinking!) :p I'm not defending what happened in no shape or form, but you watch practically any game on the TV in Scotland and at some point, someone will lob something at a player. This is not an isolated incident and it has to be stamped out across the board.
Years ago I was on First Aid duty at Ibrox for a game, this is before the sides were filled in. we used to hide behind a wall until we were needed as the volume of objects that were going between the two stands were something to believe (I'm, pretty sure we won that night as well).
It is stupid and has to be stamped out of the game.