so I'm very surprised that ASIO and the AFP don't already have a direct tap into AUSTRACs database for the purposes of background checking for an ASIC.
They do, but
AFAIK AusTrac don't have access to the ASIC holder database because it's not a routine check for an ASIC clearance. I think this is more about empire building by AusTrac than anything else.
The trouble with including the AusTrac record in the ASIC checks is that currently, you can only be refused an ASIC if you are convicted of a specific offence. An adverse AusTrac record is not a conviction, just cause for suspicion. I'm not saying it's a bad idea, but it's certainly a departure from the 'innocent until proven guilty' principle.
Personally, I would have thought it was more beneficial for the intelligence agencies to take a greater interest in the people working at ports and airports, but they're probably already doing that anyway and just not talking it up in the press.