I am also confused by some of the replies and things must have changed.
We have flown on Air Malta chartered flights to Corfu several times in recent years (booked through XL or Airflights), up until last year, and ALWAYS had a meal included in the flight price.
Maybe it is sign of the times and the state the charter industry if they are cutting back, or more likely the travel company who chartered them are cutting back. If I remember correctly if the flight number had a letter M at the end then a meal was included. Our flight departures were always on time and the flights including cabin staff, seats, legroom etc were good. The cooked meals were a bit basic but OK.
In fact the 2 last times we particularly chose flights which used Air Malta as we found them fine and better than some others we have been on.
On each occasion I rang the airline's Customer Services to pre-book seats, which was quite cheap, and to confirm that meals were included. If you do this make sure you indicate the flight is a Charter and the company you booked through.
Dennis