I'm not involved with Virgin, but I understand the way that their management is thinking at present.
It's simple. They need to cut costs immendiately. This means the return of the B747 Classic fleet to GECAS.
It also, regrettably, means the loss of the jobs of the crews on those aircraft.
Why only those crews? Simple. They are trying to cut costs - so to lay off qualified -400 or A340 people in favour of Classic people who have been around longer would be financial lunacy at present - and that's not taking into account the length of time the conversion process takes.
We're in 1940, Battle of Britain mode at present, people - and if you want the company to survive then hopefully those affected will be men enough to realise that. I have no doubts that if VS makes it through, they will be rehired.
Sticking to outdated union rules such as "last in, first out" is something that we don't have the luxury of complying with at present.