In which case, they'd better actually be sick as it's likely BA will demand a doctor's note (the seven days "self-certification" is likely to be viewed quite dimly). Otherwise, it's getting into the territory of EG300 "Pattern Sickness" which is a disciplinary matter.
Agree with your quote but when you might have some 2000 crew doing the same thing there is only so much a Company would be prepared or able to discipline anyway.
Sad but true.