In schools long term sickness would be covered by insurance.
This means that supply staff can be employed to cover the absence. When a teacher returns even part time the insurance stops.
The question then is whether the teacher needs to work part time.
It may well be at this point after long term sick that his/her entitlement to be paid the normal salary comes into play.
We then have a further stress on a teacher and its very difficult for a line manager in that they have to weigh up the situation.
In this case they got it wrong but in the vast majority of cases that don’t happen thank goodness