I find the fact that BA have reportedly lost £38m on the LHR-BFS route over the last 4 years very difficult to believe.
That said it is the BA's perogative whether or not they operate the route. Their decision to discontinue must have been influenced by TBI's attitude towards their long-established customers. In my experience short-term greed seldom works.
BFS has gone from a thriving regional airport with a strong and growing network to a low-cost back-water and they only have themselves to blame.