Australia only allows unvaccinated travelers that -can't- be vaccinated for medical reasons. Not wanting to be vaccinated or not "needing" to be vaccinated are not the same thing as -can't-.
No proof that vaccine will be harmful to your health == vaccine required for entry. Very simple.
The problem here is the conflict of interest. World No. 1 tennis player does not consider entry to Australia a privilege, worthy of taking a medical procedure which he does not have to perform otherwise.
Australia does not want to take many people in, and many people do not desire to enter Australia. But that ruins the idea of tournament. Which is based on assumption of admission on liberal terms.
Australia only allows unvaccinated travelers that -can't- be vaccinated for medical reasons. Not wanting to be vaccinated or not "needing" to be vaccinated are not the same thing as -can't-.
No proof that vaccine will be harmful to your health == vaccine required for entry. Very simple.