mattfalcus - I agree there is plenty more time to sell the flight, but if bookings for the coming December are much lower compared to the level in August 2010 or August 2009, then it's a pretty good signal that the flight isn't going to be profitable. In any case, if the operator doesn't tell customers by November, I suspect various EU compensation schemes kick in.
In addition, would Transun have to make any large non-refundable lease payments in August to the operating airline to ensure the aircraft is available ? If so, Transun may have made a decision that trying to flog more seats in Sept / Oct is too risky
Perhaps the customers would prefer to be told well in advance and be able to choose whether to go from another airport or not go at all ?