It's possible the security guard saw an Asian man leaving with a distressed 'white' child and put two and two together and made 10.
He could be a relative or friend, a step father, she could be his mixed race daughter who presents as very white looking (it would have been dark and hard to tell exactly what her racial profile was, especially if she was bundled up in a big coat with a hood and no hair could be seen.)
Unless the police have actually spoken to parents who have confirmed their child is missing it may not be a hoax exactly, just a horrible misunderstanding.
But it's very difficult to know what to do for the best in these situations. When you have a very visceral reaction to something that seems very 'off' to you and you know that time is of the essence, you don't necessarily stop and calmly process all the many possible explanations for what you've seen - you just act on gut instinct.
Had they both been white or both been Asian I doubt many people would have looked twice, assumed they were father and daughter and put the child's distress down to a tired tantrum. But they could easily have been witnessing an abduction without realising it.
In the case of an Asian male and white child you would look twice. Not necessarily because the man is Asian but because the child appears to be white and therefore unlikely to be his child. If it was a white man and a brown skinned child that might still happen but most people will realise it's entirely possible that the dark skinned child could be mixed race with a white father.
If you witnessed this specific incident and chose, for reasons of political correctness to completely ignore the obvious racial difference between 'abductor' and 'victim' you risk allowing an abduction to happen before your eyes.
I think in that situation I'd rather be wrong about reporting a possible abduction than be wrong about choosing to ignore an actual abduction, because I didn't want to be accused of stereotyping or jumping to conclusions.