"We don't know if it is Horton who is silly or it's the Australian media that is evil, or perhaps Australia just has a different moral standard," it said. "The message sent is abnormal and aberrant."
Horton has gained the backing of the Australian Olympic Committee and team boss Kitty Chiller after he said he had "no time or respect for drug cheats" on beating Yang to the wall in the 400m freestyle final.
"Mack obviously has very strong views about the need for clean sport, as every single one of us does," she said. "We have no intention of making an apology."
The 20-year-old also claimed his victory as "a win for the good guys", however it did little to please Chinese authorities or the country's swim team manager, Xu Qi.
"We think his inappropriate words greatly hurt the feelings between Chinese and Australian swimmers," he said, according to China's party-controlled news agency, Xinhua.
"It is proof of a lack of good manners and upbringing. We strongly demand an apology from this swimmer."
Sun copped a three-month ban for testing positive to trimetazidine, a substance normally used to treat angina, in 2014 - however his ban was not announced by Chinese authorities until after it had ended.
The swimmer claimed he was unaware it was on the banned list, and argued it had been prescribed to him to treat heart palpitations.