Sure, but Eastern is no charity, they want to make a cut as well.
The only cut they will get is what they are charging BACF to lease the aircraft and crew. If I remember rightly the IOM route is subsidised by a IOM based company. The DUS route must still be profitable for BACF with T3 operating the aircraft otherwise it would have been dropped. Especially when you take into account that BACF have decided to continue leasing the DUS aircraft to free up a E170 to operate the 3 x daily GVA from September.
Personally I am surprised that they haven't handed the DUS and IOM route to Sun-Air to operate. They could operate 4 x daily with a 32 seat D328 on the IOM and DUS route.