"Son, I understand that you are angry and might not have heard the whole story. But first, tell me what you were told, and we can take it from there," after taking her son into a private room, Wendy softly talked to him, understanding that he was angry and might not have been thinking straight.
Otherwise, he wouldn't have attacked Donald when he hadn't done anything.
When Simon heard that, he felt furious seeing how she was still defending Donald. However, he also knew not to provoke her. If he wanted to understand what happened to be in this kind of mess, he needed to listen to his mother.
She was probably at the scene when Sia got hurt.
With that in mind, he suppressed his hatred towards Donald and explained the way William told him.
"I was told that when Sia fell, Donald and his wife were with her. If they weren't with her, then she should be fine right now. Wouldn't she?"