I'm sure that BA are doing their hardest to keep slots OUT of the discussion! They know that slots will have to be given up and their job is to lose as few as possible. As with RB, WW is just doing his job.
Will this affect pax? Will it be against pax interest? Probably - but does anyone have an alternative?
Let us take an extreme example: The merger is prevented and both BA + AA fail and go into receivership. Would the other Alliances on the route say: "Gosh, we are so pleased at the reduction in competition and halving of seat capacity - that we are going to buy up all their equipment and staff and make sure that seat prices stay nice and low."
Let us take a simple example: The merger goes ahead and both carriers shed some staff and rationalise their routes and capacity. Prices drift upwards slightly - masked by the fuel price. Then pax realise that they are going to have to pay a realistic price for crossing the North Atlantic.
Then ... other carriers see an opportunity to lower prices and try to grab some of the lower end of the market.