There is a difference between justifying something and saying here is a possible explanation for why something has happened.
Justifying something implies that you are saying it is ok that it happened. I don't think she was saying anything of the sort!
It is a fact that people in china get sued when they have tried to help someone. It is well reported.
Since that is the case, it is reasonable to suggest that there is a possible reason why people didn't help.
It is not saying it is ok. It is saying that these people possibly had in mind all the stories of others who DID help someone in need and ended up getting their arses sued off.
If that is happening - it may explain why people would walk by.
It doesn't mean it is morally ok to walk by.