It could be that they think that they'll have a go whilst it's new. Afterall, they will not have established any biz relationship with new owners yet. However, all the operational people will still be the same.
My guess is that this has been building for some time and the recent govt inspired 'flap' has brought it to a head. Secondly, by trying to push this now, it will send messages to the BA shareholders that they (BA) are trying to fix things that are beyond their control. So, as always, there are multiple reasons for it.
Personally, I could not agree more. The problem is that, in any sell off, it is EGLL that will be retained by the present incumbent as being the Jewel in the crown. This will leave all the same planning and operational staff in place and trying to get them to change will not be easy.