Actually, we're in for Mike not realizing that bad things happen to people he knows.
Panel 1: As Elly helps him zip up his snow-suit, Mike tells her that they're letting him be Lawrence's 'special friend' at school.
Panel 2: What that means is that he gets to help Lawrence with his coat and books and stuff.
Panel 3: He next asks Elly how come it had to be that Lawrence broke his leg.
Panel 4: He stands there with a confused look on his face and says that he thought that sort of thing only happened to people he didn't know.
Summary: He doesn't actually learn anything from this mess; after all, he has to be told that same damned thing all over again fifteen years later. What bothers me is that Lynn skipped right over the "I think she thanked you enough" and "John makes mental notes 'cause that's the only way he can read his own handwriting" strips to have Mike express baffled remorse. Way to louse up the timeline more there, Lynnie-Baby.