No legal challenge, that's funny because it's ready to go at the sniff of ignorance to current employment laws which in recent years have changed significantly. Maybe you're not that up to date with what's come into force?
Anyhow, I'm not aware of union company councils making the contracts, that's what the BACC lead you to believe pre the 31st Jan vote. It'll be BA that'll be writing the music, not the union.
Whether the company would have gone bust or not and the timescale is no more relevant than the average daily maximum temperature in the Pitcairn Islands. Off to watch Newsnight, it's more interesting...