It's no good explaining to me why the legislation is bad. I know the legislation is bad. Quite apart from anything it robbed me of some pension benefits and a very nice redundancy agreement. It is however the legislation within which NATS has to work and you would have expected HR and Legal Department to know that.
All the things you say are probably right they just aren't allowed to form any part of the decision. You can rule out people on ability but not age. NATS assumed it could play the safety card and get away with it without being challenged, unfortunately it was. It can still play the safety card as long as it applies to the likely future performance of each individual and doesn't just use an arbitary age limit.