My understanding is that a large chunk of the $2bn is guaranteed against debt. Airlines need large cash buffers to guard against short term hiccups. There is no way that is all free cash they can spend without being technically insolvent.
JB did say about two years back that Virgin were better situated to sustain a fare war than Qantas. He may well have been correct. My guess is that the $900m full year loss would result in the Company trading insolvent, hence AJ's increased sense of urgency.