To admit that the dismissals were targeted, makes them unfair. To not, would allow IA, with the cost implications, regardless of the effect. A business decision, no more no less.
I dont understand? Why do BA have to do either? It was the union that linked the dismissals with the previous IA not the other way around. They are also the ones that need new grounds for a dispute. BA can just say this was used as a justification last time so its not new. Nothing else need be said.