If the NBA wanted to start policing gestures, this slanty-eyed picture doesn't even compare to something like
Vlade Divac's hand gesture. Where was the outrage when Divac did a gesture about 10,000 times in his NBA career?
There wasn't any even though that gesture can be interpreted as being much more offensive than what the Spain basketball team did. Why wasn't there any outrage? Because as Americans, we had no idea WTF Divac was doing.
So unless the NBA wants to hire race relation experts from each country to figure out what is or isn't considered racist in a given culture, it's best to keep that can of worms closed. Police what you know but don't go out searching for racism or other forms of prejudice to crack down on. It won't work.