I think the real issue is Hollywood's "Not Invented Here" attitude, though. A television series based on New Frontier wouldn't have looked much like the novels, true, because producers and execs would want to put their stamp on it. It's possible the production team could have brought PAD in as part of the team, but what's more likely, imho, is the MCU situation, where the Hollywood people would be credited and paid, while PAD would get a "special thanks" credit and no money. Paramount, after all, already owned New Frontier lock, stock, and smoking barrel as a tie-in project. They legally didn't owe him a dime if adapted.I recall PAD resisting calls for "New Frontier" to become a live-action series. He was convinced that, in the very unlikely chance that it got made (as in "never"), the way that most TV series are made by committee would mean that it would not bear much resemblance to his NF novels.
Stone is a character I really wanted PAD to revisit, and he never did. As the years went by and more New Frontier books were published, I think similarities between the characters disappeared, just because Calhoun was better developed.While writing TNG's "A Rock and a Hard Place" (1990), Peter David had considered several titles for the book, including... "Space Case". Within the novel, the descriptor of "space case" was given to the aloof First Officer Quintin Stone. Years later, I tried to confirm with PAD that Mackenzie Calhoun was seemingly an evolution of the previous Stone character, but he denied it. Which quite surprised me.
Both characters were based on Mel Gibson, but Stone is Gibson from Lethal Weapon while Calhoun is Gibson from Braveheart, though PAD really wanted him to be based on Han Solo and Paramount said no. Also, PAD's first wife, as he notes in the intro to Rock and a Hard Place, said there was a lot of PAD in Stone.