If a player signs an NBA contract (whether guaranteed or not, and whether they play in the NBA or not) their rights are gone. This applies to Iverson, Bentil, and Jackson. Because we've signed them, their draft rights are gone forever, and the Draft Rights Rule does not apply to them
If a player doesn't sign an NBA contract, we retain their rights and they're free to play anywhere. The D-League is one place where they could play, but they don't have to. They could either play elsewhere (Europe, China, or Australia), in which case we retain their rights, or take a year off (which is almost never a good idea) and enter next year's draft. For example, Nader can choose to play in the DLeague, or go oversees like Colton Iverson or Marcus Thornton. There's no limit on how many players we can do that with (AFAIK)
The second part you quoted is affiliate players, which (if I'm not mistaken) are different. Those are simply players that, after cutting them from our camp roster, are allowed to either play overseas or play for our DLeague team (they can't play for another DLeague team). We don't have their rights, though, so they are eligible to sign with any NBA team. In 2014, we did this with Tim Frazier, Rodney McGruder, and Christian Watford. Bentil would be eligible for this, but I think he'll either find a spot on another NBA team or play overseas if he doesn't stick with us