I tend to agree with this point of view. Prince William will likely be King one day regardless of whether or not Prince Charles precedes him. Ergo, it hardly seems "unusual" that his grandmother Queen Elizabeth and his father Prince Charles would be grooming him at an early age for his future role as monarch.
Moreover, while I am not a big fan of Prince Charles, if reports I have read are to be believed, there seems to be a great deal of affection between Prince Charles and his sons. William and Harry seem like such nice young men. IMHO, neither one of them appears to be the sort of person who would do anything to disrespect or personally humiliate their father.
Unless I misunderstand succession, if Charles surrenders his claim to the throne, he surrenders it on behalf of his heirs — putting Andrew, not William, next in line, and Beatrice and Eugenie behind him.