MrBendip, you're right but WW knows that LH's options to dispose of BMI are very limited. Given how precious LHR slots are, ordinarily BMI should have been a dream ticket for access into the prized LHR and so I would expect BA to be very interested in helping LH offload BMI......however even WW will only do this if the price/deal is right.
WW holds all the cards and knows that when it comes to the slots, he can either pick up BMI for the right price now, or alternatively he can pick up the slots at a later date. WW is in no rush and perhaps he knows that BA is one of the very few, possibly the only option that LH has left.