Hello I am not sure I agree with your recollection of the BA involvement with LCY. The route was operated by Aer Arann until April 2012 and then BA took it over in May 2012. At this stage there was no underwriting to my knowledge. They continued with the route until July 2013 when they moved the SAAB 2000 they were using on the route to set up a new DUS-LCY route. At that time they continued with the IOM-LCY route using an Embraer 170 albeit once a day mostly mid morning.
It was only after protracted negotiations and the efforts of a lot of people to get it back that they then reinstated a three times daily service with another SAAB 2000 that they leased from Eastern.
I still say at least the IOM currently get a reliable three times daily service with early morning and evening slots and it should be encouraged. Also worth noting that when needed because EZY shift there aircraft elsewhere for the summer BA put on additional rotations.