Because redheads are so unbelievably common in Ireland, calling him the "smartest redhead in Ireland" is a clever little joke that draws a contrast between his

Because redheads are so unbelievably common in Ireland, calling him the "smartest redhead in Ireland" is a clever little joke that draws a contrast between his exotic intelligence (building an AI system, desigining a programming language) and his incredible ordinariness (having red hair in Ireland).