Lets see whether it holds up under law and my guess is that it will not as will be seen as arbitrary with no basis for the fine.
They will be faced with proving everybody else was taken care of by every airline as a reason why no one else was fined nor treated in same way.
Think this as you point out is an attempt at revenge based on row earlier and believe its has likely only one outcome with fine being overturned in court on basis they have no legal right to fine anybody based on lack of clear evidence.