This really sounds like something that CASA should have been all over; monitoring the company in the immediate aftermath of his licence revocation and taking necessary enforcement action.
I would guess that if nothing untoward appeared on the paperwork, then the CASA had no compunction to intervene. In the past 35 years or so, it seems that the CASA's modus operandi has been "pro-active and pre-emptive". If the paperwork is fine, then there is nothing wrong with the company or the person. (Heavy on sarcasm.)