SHVC, it would be ego surely wouldn't it?
Here's a scenario for you. What if B thought (rightly or wrongly) that he was the genius who turned
VB into VA, and he felt like he deserves all the credit. Then along comes T and everyone touts him as the heir apparent, the great shinning hope, the best thing since sliced bread. B, sniffing the wind feels a profit on the horizon. To ensure that B gets the glory he feels he deserves he offs T. Otherwise everyone will say when that profit eventually turns up "you see T saved us from the abyss!"
Either way the rumours are all pretty strong that it was an irreconcilable personality conflict.
B won't leave until the company turns a profit and he can go out as the messiah of Australian aviation.