"Why shouldn't the Aboriginal flag be recognised internationally?"
Each country has only
one National Flag. The Aboriginal Flag represents our Aboriginal people, estimated 864,000 of our 25 million population, or 3.5% of our population. The Torres Strait Flag represents the interests of our 38,700 TI Islanders, or 0.15% of our population.
We also have nine official flags representing each of our States and Territories. How many flags do you think Australia should expect to be recognized internationally? How many flags do you want placarded on the side of Qantas aircraft?
We are proudly a nation with diverse ethnic and cultural heritages, but in all respects internationally Australia is
ONE Nation with
ONE recognized National flag.
https://en.wikipedia.org/wiki/National_flag