Every stock I have ever seen, the settlement time never came into the figuring of the div payout.
Example:
Have to own stock by Wendsday to get div.
If you are in by Tuesday close, you get div.
If you sell before Tuesday close, you are out, even though the money clears 3 days later. (Settlement of money has nothing to do with it, buy or sell.)
Another example.
A stock is halted on Wednesday, and shut down by the SEC and never alowed to trade again.
One person bought on Tuesday, another sold on Tuesday. Neither person has had the money clear yet for the trade. The person who sold before the halt, and has not had the money clear yet from the trade still gets his money. The person who bought before the halt and has not had his money clear yet, still gets the shares.
I have never seen any div be determined by settlement date.