Autistic people see the world in very literal, linear ways. He told her not to get the fish. Now she's having difficulties with them. In his mind, it serves her right bc she didn't do what he thought she should do. So he feels justified in letting it be her problem. Kind of, "you made your bed, now you lie in it" thinking. "Not my problem."
that makes sense BUT she is also his mother and getting older which he needs to try and wrap is head around.