Well, to be very brutal... The (North Vietnamese) got what all they could get form the Aussies ... The vets and families had already traveled to Vietnam, had spent their money (most of it) already, and will have to spend more of it in Vietnam going home. And waiting for their plane flights back out.
In a country that values “saving face” as they do, this is an insult to the whites. Another Vietnamese war victory over the white capitalists.
That’s certainly not impossible, but it would be a matter of killing the golden goose. More and more Australians make the pilgrimage to Vietnam every year - for many of the veterans in their 70s, they know it’s their last chance and not all have gone for Long Tan - though pivotal in Australia’s time there, to individuals it can be far less important than where they served themselves. And their kids are going as well. Economically from a Vietnamese perspective I’m not sure this makes sense and so I’m not sure that is what is behind it. Seems more likely someone has taken offence at something, whether justified or not and nobody is talking about it right now.