Bill Kennedy appears to be ignorant of the long established tradition in the British aristocracy that the wife's first duty is to bear her husband a son*, who will inherit the family fortune and his name. Once that duty has been fulfilled, it's always been open season on both partners as long as they are reasonably discreet about it.

It matters not who Prince Andrew's father is, nor Harry's.
Look at the first sons: Charles and William's fathers are who they are supposed to be, and it's a fairly safe bet on this occasion that the new Royal baby is William's too.

*presumably it doesn't have to be a son now; if a daughter is good enough for Royal accession, she's good enough for inheritance of the family fortune too.