I don't know the terms of Gibson's contract and gladly accept I may be wrong in this instance however some years ago I was given a model, typical Form of Contract supposedly used as the basis for negotiation for player's contracts. It states that a player's contract may be terminated immediately and without notice if the player is guilty of serious misconduct which in the Club's opinion may injure the reputation of the club.
It also makes mention of "persistent breach" ... and I seem to recall Gibson's been associated with drink related, bawdy behaviour before.
Talk of rehabilitation, seeking help etc are normally exactly that .. talk. Most employers in this situation normally want to get rid of the problem without too much fuss.
Everton have got to be very careful too given past (aforementioned) 'indiscretions', we don't want to be seen as a soft touch amongst players or encourage similar behaviour amongst the younger millionaires.