This guy is stupid. Technically, William does only need to live long enough until George is 18 to avoid Harry as a regent. Harry only has a chance to become king one day if desaster strikes, his brother already has 3 children, so no need to fear a king Harry.
ans a queen sparkles
Yes, while he had a very few good points to make, he was addressing a very conservative audience and played up their fears with some bogus nonsense.