Did the indigenous people call it Australia? If not it would be no more racist than proclaiming the USA est. 1776. (Although I feel quite sure there are those who would call that racism as well) face it. They are going to call racism no matter what you do, so why let it bother you?
This is more like saying "America, est. 1492" (or 1607 or 1620).
As we see every Columbus Day or Thanksgiving, yes, there are people who would call that racist.
1776? Maybe we're headed to the point where that will be seen as racist as well, but we're not quite there yet.