No, it's one that comes up in OLCI as requiring specific consent that you are fit, able and willing.

I think what happened was that they found a suitable WTP passenger and upgraded her without realising that she had an exit seat, or she said she was fully fit (I think I'd have been tempted to say that in her position!), or her physical condition wasn't obvious to the gate agent at the time of the switch - and the gate agent probably didn't have quite the extent of medical diagnosis techniques as the Original Poster. Bearing in mind this was probably all done with a degree of background chaos which is not unexactly unheard of in India.

Given the hypothesis that we are talking about I don't see how it would have benefit BA to lie about it, equally there is no benefit to BA is hassling the OP unnecessarily.