It is commonly used where I am from.
Unless otherwise stated, most people come to this forum wanting to know about the English used and accepted in such places as Australia, Canada, Ireland, New Zealand the UK, and the USA. Forms accepted in Malaysia but not in the countries I have mentioned are not normally what they are looking for.
Tdol in his post in the thread you give, acknowledged that too, as someone who have had long experience living in Asia.
We do not normally deal here with The English spoken in Asia. Tdol also said that it sounded strange to him when he first went to Asia.
People would frown at me if I were to say "I am a Chinese person".
I doubt if they'd frown, but they might not find it natural. That's because it's far more natural to say "I'm Chinese".