See comment for reasons

Reasons:

1. Djokovic had a three year ban from Australia for being an Anti-Vaxxer due to breaking the vaccination rules of Australia one year ago.

https://time.com/6138074/novak-djokovic-australia-visa-covid-19-vaccine/
https://www.nbcnews.com/news/world/novak-djokovic-australian-open-visa-rcna57637

2. Djokovic refused to isolate from COVID-19 on the December 17 and Christmas Day.

https://www.theguardian.com/sport/2022/jan/08/novak-djokovic-relied-on-december-covid-infection-for-vaccine-exemption-court-documents-reveal

3. Djokovic is a COVID denier.

https://nowtoronto.com/news/novak-djokovic-becomes-a-poster-boy-for-the-anti-vax-movement-but-hes-not-the-covid-denier

4. Attacking Anti-vax sentiment is not discrimination.

Vaccine mandates that have been in place is not discrimination as it is a part of being an adult.

There are some jobs where mandates have been in place even before COVID even existed, and yet that hasn't been labelled as "discrimination"...

If you are a taxi driver, you need a license to drive a taxi. If you are a teacher, you need a Working with Children Check card. If you are an aged care or a nursing home worker, you need the flu jab.

But that's not discrimination, its a part of being an adult/

https://www.theguardian.com/australia-news/2021/nov/22/one-nation-anti-vaccine-mandate-bill-rejected-despite-support-from-five-coalition-senators