This is hardly the no-brainer some make it out to be. Giving up that pick and it turning into Michael Porter while PG signs with LA next season would be a disaster for Danny Ainge.
Ainge has to be sure PG will resign with him before he gives up that pick. And I don't know how he can be. All this "he won't leave a great team" noise won't matter if Lebron convinces him to join him in their new hometown. When a guy tells you repeatedly that he wants to go to LA, maybe he means it.
Regardless, this is likely just Ainge posturing in the media in response to Indy overplaying their hand.