In this passage, the speaker is surprised and possibly amused by Mr. Rock's emotional display, finding it unusual or unexpected. The use of "did me in" suggests that Mr. Rock's emotional moment had a strong impact on the speaker, perhaps catching them off guard.
The quote highlights a rare vulnerability from Mr. Rock, emphasizing the significance of his feelings in that moment. It shows a shift from what might typically be expected from him, making it a memorable and noteworthy scene in the story.