Originally Posted by
Andriyko
Apart from the obvious capacity explanation (that lounge can barely accommodate F passengers), AY may simply not want to pay for access to BA lounges in addition to the negotiated access to AF/KL lounge.
According to oneworld rules, that's not their choice to make if alliance rules say that certain passengers are entitled to use any partner lounge. However, airlines/lounges have been known to prevent someone from going lounge hopping at an airport with the airline being forced to pay multiple lounge fees.