The judgement will help BA maintain the operating profit it achieved in the last quarter, which without the changes would probably have resulted in a bigger loss. A step in the right direction to keep BA afloat - good for all employees I would have thought?
As for agreements - as has always been the case if it is not in black and white in your contract - don't rely on it. Nothing in law has changed as a result of this judgement, it is a merely an interpretation of current law.