The league has a history full of players who "paid their dues" yet still didn't get a ring. In my opinion, a ring is "earned" in the course of a single season - you don't "deserve" a ring just because you play in the league for 15 years. Malone had his chance to get a ring. THREE times in fact.
Barkley, Malone, Mourning, Kidd, Ewing, Miller, 'Nique, Lanier, Alex English, Gervin, D. Thompson, Stockton - none of these guys have rings, even though they are hall of famers.