@izzythepush,
Well, it's not exactly a far fetched claim (after all, it's not hard to imagine Australia benefiting from US contracts), although properly phrased - it would only be one of many considerations regarding Australia going to Vietnam.
But more to the point, since WW2, Australia has always supported the US in it's Military strategies/wars.
Prior to WW2, Australia always supported Britain in it's military strategies/wars.
The world was changing and Australia, which is a vast and underpopulated country, does not have the military ability to properly defend itself from invasion. So it has always looked to a protector. The only way to ensure that is to publicly bind itself to that protector.
Quite frankly, if Indonesia decided to build a flotilla of small craft, and send a few million farmers to take over and develop the west coast of Australia, I doubt there is anything anyone could do to properly stop it. Australia steps very carefully around Indonesian 'politics' - despite the atrocities that have occurred on our doorstep at the hands of the Indonesian military (ie. their 'politics' - in Indonesia itself, in East Timor, and in West Papua - the latter which is still an occupied country that is in no way shape or form, Indonesian).