What do you want them to say?
‘The First Officers kid fell sick so he won’t be in today as his wife needs to work also so your flight is now cancelled’
Operational or Engineering excuses will do just fine.
I once had a CC member go sick during a turnaround, now the ground crew advised the passengers in the terminal it’s cancelled because a crew member feels ill and needs to go home. Now as we walked through the terminal back to our cars we copped a whole heap of abuse walking past 200 people. Please just blame weather...atc...engineering..whatever..next time thanks.