It may have been a better move not to dismiss him and it still may turn out to be an unfair dismissal. It certainly has not removed him from the dispute.
Sorry to say, Duncan Holley has already taken BA to an industrial tribunal for unfair dismissal ... and lost. Hence his current boasts that BA can't control him. My understanding (and a BASSA member may be able to correct me on this) is that his position as branch secretary was due for election just before this dispute began. The decsion was taken to defer all elections until after the current dispute had ended. He is able to cling on to his job as branch secretary despite not being employed by BA as I beleive Unite allows branch secretaries to be appointed by the union as a short term measure pending an election. Perhaps Litebulbs can confirm this.
BASSA should indeed be worried at the rate that they are losing members and new staff are joining Mixed fleet. If BASSA call a strike for crimbo which results in strikers getting sacked, the replacements will be more mixed fleet folk. I would bet that this would also be the point at which more members resign the union, so could prove to be the final tipping point to derecognition. A pity really as there is clearly a need for a strong union in this area and a revived BASSA with new blood in the executive might mean a more foward looking union, but the way this is now shaping up, I can only see one end result.