The question to ask is, what was the sick leave situation like before they announced the closure? If it was similar to now, then they've had a problem for a long time. If it has only become an issue since they announced the closure, what did they expect?
The workers may have not taken too many sick days over the years, but now there is no incentive not to take them. They're just showing the same amount of loyalty that has been shown to them.
If management could not see that this was going to happen, well they're just as thick as the rest of the management at QF.