Er?
You can't take people off a legal day off because that's exactly what it is...a legal day off! If he's printing stuff like that on the portal, maybe a screen shot to the GCAA, CAA, FAA and any other AA may be in order. If they didn't work them to the bone, gave them what they bid for and employed sufficient numbers, they might not be in such a mess. Stop marking them absent and removing them from flights when they're 1 minute late would also alleviate this self generated problem. Hardly rocket science.
But that may mean having to give up their bonus when the budget is exceeded, a sacrifice most senior managers would not accept. When it comes to integrity vs personal greed, the latter wins almost every time.
Having said all that, when 500 confidential reports and ASR's are received within 3-4 months highlighting certain issues, maybe they'll listen. Apathy is our worst enemy. Crew DO have the ability to influence change, if they can really be bothered. Moaning doesn't get you far, reporting may get you further.