I don't remember saying that????? I guess "closely related" is relative. If you're comparing a percula and saddle back to...... say........ a shark, then yes. The percula and saddle back would be more closely related. If you're comparing percula and saddle back to an ocellaris, the percula would be more closely related to the ocellaris than to the saddle back. Saddle backs are more closely related to sebae anemone fish.
I've never seen a successful pairing between saddle back/A. polymnus and percula. That doesn't mean it hasn't happened, or that it can't happen. If you're successful, they would probably produce some pretty sweet looking clowns. The way I see it, if you go by the scientific classification of these fish, there's no known reason why such a pairing couldn't be successful. Ocellaris has been successfully bred with P. biaculeatus/maroon clown. Saddle back and percula should be more closely related than ocellaris and maroon, so why not?