I was thinking it did ok finding a "joke" in text that doesn't really contain enough context for there to be a "joke" but really, if its wordplay it should be based around the difference between the subject of "I'm." As in, is person 1 telling person 2 to say "[person 1] is a security guard" or telling person 2 to literally say the words "I [person 2] am a security guard." So it didn't even manage to connect its own ideas together in a way that makes sense