Why did Su Ming tell Ororo all this?
Besides standing up for Little Cousin, there was another important reason: to manipulate Storm's emotions.
As mentioned before, Storm had survived a plane crash as a child, then been controlled by a gang of thieves and lived through a long period of misery.
Batman had fallen into the Batcave when he was young, and the bats in the darkness had become the source of his fear. Even he couldn't withstand that kind of trauma, so others had even less chance.
Thus, anyone who truly understood Storm—or rather, anyone who had read the comics instead of merely watching the movies—knew she had one greatest weakness.
Claustrophobia.
Perhaps watching her parents get smashed into pulp when the small airplane cabin crashed had been too traumatic; perhaps the time she later spent imprisoned in a basement by a criminal organization had been too unbearable. All of it had left her with severe psychological scars.
Even now, Ororo could not enter dark, narrow, enclosed spaces, such as sewers, cellars, caves, and the like.
Once a similar environment triggered an episode, she would immediately lose all combat capability, trembling all over and weeping uncontrollably. It was a chronic condition that even Charles could not cure with Psionic Power.
The little bald man was helpless, and even Oshtur had no solution for human psychological problems. The Vishanti were formidable, but none of their authorities involved mental powers.
But Su Ming could do what neither people nor gods could.
Deathstroke knowing everyone's weaknesses was no joke. Used properly, that knowledge could kill people, but it could also help them.
Storm had always been a good person. No matter how picky one was, aside from being a thief as a child, there was nothing else bad to say about her.