This is a typical case of Chinese style communication.

First I don't think it is "運動員之間有點小碰撞本來很正". Usually people avoid body contact in water unless they know each other.

Second, the Brazilian woman is wrong wearing flippers in water, but it doesn't mean 孫楊 can grab her. That action is inexcusable and ruined any chance for 孫楊 to make a legit complain against the Brazilian woman. After all, did she commit any atrocity other then wearing flippers? Can he be a gentlemen and forgive her?

The truth is he does't have to forgive her. He could have made a complain to security guards and asked to remove her from the pool. That is his legal rights.

What he did, however showed that he maybe talented as a swimmer, he is very foolish, rude and self-centered as a person with absolutly no class. He is lucky she didn't sue him for any injury.