How would you feel if your daughter said this about your step son

My daughter is 15 my step son just turned 16. He's kind of a weird kid. He was a huge mamas boy but his passed away back in 2016. He has stuffed Winnie the Pooh that he keeps near him at all times. My daughter has stuffed animals too so I try not to side eye buy I still catch myself doing it. He lost it one day and couldn't find it and he had a whole mental break down. My husband went on a hunt for it and turns out he left it at my sister. He gave it back to him and he calmed down but was still upset so he went in his room to go to his "happy place". I've seen pictures of his happy place that he's drawn and my daughter said "Every day he doesn't snap and kill us all is a miracle". That alarmed me. Is my daughter actually afraid he would kill us?! That just threw me off.

Before anyone suggests it, he's in therapy